Opinions about stirring sand or gravel during weekly water changes?

[bekateen]

Hi All,

Following on the tail of another thread (Plecos dying! ), I have a question about your opinions on what you consider good practice, or even best practice, when it comes to keeping gravel and sand clean in an aquarium.

Myself, my views have evolved in the year that I've been on this site. I started with two or three tanks, each with a deep layer (6-8cm) of sand or fine gravel for substrate. But now my seven tanks have much less substrate (1-2cm avg depth, sometimes pushed into mounds by fish, creating deeper areas (up to 6cm max)).

When doing water changes, I have a habit of stirring up the sand or gravel very thoroughly, with the reasoning being three-fold:

1. This liberates any toxic gases which may have built up in the substrate;
2. More for gravel than for sand, this resuspends tiny particles of feces and waste into the water column, so that as the water change occurs, this debris can be washed out of the tank... hopefully resulting in a cleaner tank when I'm done; and
3. This undoes any landscaping done by the fishes, leveling out the substrate so that it is uniformly shallow throughout the tank.

I have read that some aquarists disagree with this strategy, arguing that it kills the beneficial bacteria in the gravel, and may lead to an ammonia or nitrite spike for the fish in the tank; I've also heard that by releasing potentially toxic gases, it risks poisoning the fishes.

Counter to these concerns, my experience tells me that I can move this used sand/gravel from one tank and place it (along with an aquarium filter filled with old media from the same tank) into a brand new aquarium, which essentially creates a tank that is "cycled" within a day or two of its setup (especially if the fish load will be small for the size of the tank). The logic here is that the beneficial bacteria are attached to the sand and gravel, so stirring up the substrate has relatively little long-term effect on the bacterial load of the tank. The other benefit here, from my perspective, is that if harmful gases are accumulating in the substrate, it's because that area of the tank has become stagnant with decaying organic matter and (mostly anaerobic) harmful bacteria. So by stirring up the substrate, (A) the gases are released before they accumulate further, (B) the organic debris is stirred into the water column, where it can be washed away in the water change, and (C) the exposure of the substrate to oxygenated water will kill some of the anaerobic bacteria, and even if not much, it will disrupt the local anaerobic environment so that these bacteria won't recolonize as fast after the water change (I realize that some of the bacteria are facultative anaerobes, so they may still survive when exposed to oxygenated water, but at the very least it will force them to switch from anaerobic pathways which produce toxic gases to aerobic pathways which aren't as harmful).

So what your practices? Opinions? Experiences?

Cheers, Eric

[TwoTankAmin]

The key to it all is how deep the substrate is as well as how fine the rain/pebble size is. Unless one has live plant in their substrate, it wont have sufficient oxygen to support aerobic nitrification by about 1/2 inch deep. So with shallow sand or gravel turning it over wont kill off any bacteria. Nor will there be sufficient spaces for anaerobes to colonize. Stiring up shallow sand helps prevent a build up of organics which may be unwanted for just the reasons you stated and should not harm the bacteria.

When one has a deeper unplanted substrate, the possibility for developing anaerobic bacteria which produce hydrogen sulfide increases. There with these the idea is not to stir things up below 1/2 inch down and one should be fine. Once way to prevent this, to some degree, is to keep something that burrows in the substrate stirring it up. Maylasian Trumpet snails would be an example.

I would suggest to anybody who thinks they might have trapped gas in the substrate and wants to clean below 1/2 inch do the following. When you push the siphon in, hold it a few seconds to see if any gas comes up in the tube. I would never deep vacuum the substrate in a plant tank, however. There is a whole balanced eco system down there that works great and there is nothing to be gained by disturbing it.

One, man's opinion here, as always.

[dw1305]

Hi all,

The key to it all is how deep the substrate is as well as how fine the rain/pebble size is. Unless one has live plant in their substrate, it wont have sufficient oxygen to support aerobic nitrification by about 1/2 inch deep. So with shallow sand or gravel turning it over wont kill off any bacteria. Nor will there be sufficient spaces for anaerobes to colonize. Stiring up shallow sand helps prevent a build up of organics which may be unwanted for just the reasons you stated and should not harm the bacteria.

When one has a deeper unplanted substrate, the possibility for developing anaerobic bacteria which produce hydrogen sulfide increases. There with these the idea is not to stir things up below 1/2 inch down and one should be fine. Once way to prevent this, to some degree, is to keep something that burrows in the substrate stirring it up. Maylasian Trumpet snails would be an example.

I would suggest to anybody who thinks they might have trapped gas in the substrate and wants to clean below 1/2 inch do the following. When you push the siphon in, hold it a few seconds to see if any gas comes up in the tube. I would never deep vacuum the substrate in a plant tank, however. There is a whole balanced eco system down there that works great and there is nothing to be gained by disturbing it.

I think that sounds a pretty good approach. Personally I only have planted tanks, and they all have MTS in them, so I don't syphon through the substrate.

In some of the high flow tanks I've had areas of fine gravel (where the current has sorted a mix of sand and gravel), and I did I syphon through these occasionally (with the filter turned off). With sand any organic debris should sit on the top of the substrate.

cheers Darrel

[bekateen]

When one has a deeper unplanted substrate, the possibility for developing anaerobic bacteria which produce hydrogen sulfide increases. There with these the idea is not to stir things up below 1/2 inch down and one should be fine.

So this gets to half of my question: If you DO have sand or gravel which is deeper than 1-2cm, and you suspect anaerobic bacteria might be building up, along with toxic gases, why would you leave it there? Obviously you wouldn't want to release the gases into the tank and leave them in the water, so between water changes you would work to keep the gases trapped safely away from the fish. But if you're doing a major water change, wouldn't you want to expel the gas and disturb/suppress the anaerobic bacteria during the water change?

Personally I only have planted tanks, and they all have MTS in them, so I don't syphon through the substrate.

Sorry, I should have been more clear: Reframing my OP more carefully, I was specifically asking about non-planted tanks, or tanks with un-rooted plants (floaters or plants in their own pots, or those attached to driftwood, etc.). I understand the value of stable substrates for rooted plants.

Cheers, Eric

[Jools]

I learned about this the hard way with a large colony of clown loaches. My view these days is that it's like algae. It's something natural that happens. When you wander around in bodies of water in the wild, you disturb lots of gas from the bottom of slow flowing or still waters. Nowadays I don't actively try to disturb it in tanks with deeper sand, some tanks with burrowing fishes naturally turn it over, but those without do not and that's fine with me.

I do think that the addition of an airstone reduces or negates the effect of gas release which, total guess and some science would be good, harms fish more through rapid DO depletion than poisoning.

Jools

[TwoTankAmin]

1 inch = 2.5 cm. I see no risk at all with a a 2 cm depth. I have been using sand in tanks for a while now, mostly in pleco spawning and growout tanks. But also in a couple of others as well. In some the sand is spotty- i.e not everywhere. In most it is covering the entire bottom at depths ranging from .5 to 1 inch. I have never ever seen a hint of anything anaerobic.

I also have to pull apart the pleco tanks a number of times a year. I remove fry from breeder tanks to grow tanks and from them to new homes. This allows me to vacuum under the decor which has been removed to facilitate the catching of the fish. The substrate will get a good vac at that time.

When you are stirring up the sand to let the gunk into the water to be dealt with by the filter, it is similar to the principle used with reverse flow under gravel filters. The flow up through the gravel keeps a lot of the solids in the water in suspension which lets them be removed by another filter.

[dw1305]

Hi all,

My view these days is that it's like algae. It's something natural that happens. When you wander around in bodies of water in the wild, you disturb lots of gas from the bottom of slow flowing or still waters. Nowadays I don't actively try to disturb it in tanks with deeper sand, some tanks with burrowing fishes naturally turn it over, but those without do not and that's fine with me. I do think that the addition of an airstone reduces or negates the effect of gas release which, total guess and some science would be good, harms fish more through rapid DO depletion than poisoning.

I think that is a pretty good summary of the scientific position as well, universally deep substrates will have negative REDOX potentials, a deep sand bed will act as a plenum <"http://www.skepticalaquarist.com/freshwater-plenum"> where anaerobic microbiological denitrification (reduction of NO3 to N2 gas) will occur (the gas bubbles will largely be N2, rather than H2S) and H2S poisoning is only likely to occur in a limited range of circumstances.

I think that there are risks to a deep substrate without plants, I also agree with Jools that this largely relates to their role in the possible depletion of dissolved oxygen, and that this risk can be reduced by not disturbing the substrate.

I know I've posted link before but we are in Winogradsky column territory (<"http://archive.bio.ed.ac.uk/jdeacon/mic ... nograd.htm">).

1 inch = 2.5 cm. I see no risk at all with a a 2 cm depth. I have been using sand in tanks for a while now, mostly in pleco spawning and growout tanks. But also in a couple of others as well. In some the sand is spotty- i.e not everywhere. In most it is covering the entire bottom at depths ranging from .5 to 1 inch. I have never ever seen a hint of anything anaerobic.

If you don't have rooted plants I would definitely only have a shallow substrate layer.

When you are stirring up the sand to let the gunk into the water to be dealt with by the filter, it is similar to the principle used with reverse flow under gravel filters. The flow up through the gravel keeps a lot of the solids in the water in suspension which lets them be removed by another filter.

Again not every-one is going to agree, but I would very strongly recommend not using your filter as a syphon.

cheers Darrel

[amiidae]

For me.. I keep it less than 3/4inch thk and I would stir the gravel during water change.

Anything more, I would put a under gravel filter below it.

[Viktor Jarikov]

When you are stirring up the sand to let the gunk into the water to be dealt with by the filter, it is similar to the principle used with reverse flow under gravel filters. The flow up through the gravel keeps a lot of the solids in the water in suspension which lets them be removed by another filter.

Again not every-one is going to agree, but I would very strongly recommend not using your filter as a syphon.

Out of curiosity, would not the gunk be trapped in a mechanical prefilter, which is cleaned / switched frequently anyway, thus leaving the main filter unaffected?

[dw1305]

Hi all,

Out of curiosity, would not the gunk be trapped in a mechanical prefilter, which is cleaned / switched frequently anyway, thus leaving the main filter unaffected?

Viktor it would. The problem for me would tend to be "out of sight, out of mind", once the gunk was inside the filter.

If you are in a situation where your dissolved oxygen levels are already sub-optimal even a short period of low flow may tip the tank, and its inhabitants, over the edge. Oxygenation is different from everything else, because it has to be right 100% of the time.

If you have pre-filter sponge on the filter intake, and even better, a really big PPI10 or PPI15 pre-filter sponge, then I see no problem with that acting as a mechanical filter. Cleaning it will take seconds, and it can be done every day/couple of days, during water changes.

cheers Darrel

[Viktor Jarikov]

I see. Oxygen again Thanks to you, Darrel, I've come to realize that I have grossly, very grossly underestimated and did not understand even the basics of the oxygen issues in our hobby. My fish paid the price for my ignorance but, many thanks to you, I believe I am getting better.

I've always been a sump guy too but thanks to you I've started building my first wet/dry filter for my 10,000 gal koi pond, 20,000 GPH.

[bekateen]

The problem for me would tend to be "out of sight, out of mind", once the gunk was inside the filter.

If you are in a situation where your dissolved oxygen levels are already sub-optimal even a short period of low flow may tip the tank, and its inhabitants, over the edge. Oxygenation is different from everything else, because it has to be right 100% of the time.

I too like the pre-filter design, but sometimes I don't have the time to maintain them, or my kids (who help me maintain some of our tanks) miss them, and as a consequence the filters clog occasionally. For that reason, I've started relying more and more on aeration mechanisms (like airstones or powerheads with venturis) which function independent of filter mechanisms. So far (knock on Repashy Morning Wood), I've never had an aeration systems clog, and when my pumps have clogged, I've not yet lost any fish in tanks which also had independent aeration systems. Contrast this to the disaster I had last January (Is there a way to "decontaminate" Ich-exposed plants?) where I had a filter clog in a tank without a separate aeration system: a lot of fish died that day. Something I never wish to repeat, if I can avoid it.

[TwoTankAmin]

The problem with clogging the intake side of any "pump" is it can cause damage. One should always control flow on the output side unless you have a variable speed control that is a part of the pump or powerhead.

In 2001 - 02 I was an active chatter on a now defunct site. One of the members there worked in the pump industry. However, he worked with the hige industrial size pumps, the ones with pipes a man can walk through w/o stooping. The one thing he pounded into out heads was the facts I related above. He was also a bug about flow around in hobby filters.

If you use pre-filters, it is very important to rinse them regularly to prevent any meaningful intake flow reduction.

Maybe you can make a big sign for the kids on the wall that says: Did you rinse out All the intake sponges?

[bekateen]

The problem with clogging the intake side of any "pump" is it can cause damage. One should always control flow on the output side unless you have a variable speed control that is a part of the pump or powerhead....

If you use pre-filters, it is very important to rinse them regularly to prevent any meaningful intake flow reduction.

Maybe you can make a big sign for the kids on the wall that says: Did you rinse out All the intake sponges?

Indeed, that would be appropriate as much for me as for the kids.

Cheers, Eric

[bekateen]

My view these days is that it's like algae. It's something natural that happens. When you wander around in bodies of water in the wild, you disturb lots of gas from the bottom of slow flowing or still waters. Nowadays I don't actively try to disturb it in tanks with deeper sand

But I would think the difference is this: In nature, unless you're talking about a small, isolated body of water, the sheer volume water associated with a stream or pond would tend to dilute the effects of any gas release and help prevent fish poisoning, unless the fish are in the immediate area of the gas or trapped in a microhabitat, like under a rock or in a cave.

Don't get me wrong, I'm not advocating deeper gravel anymore (maybe that would have been different if I could get my plants to grow better). But it just doesn't seem wise to leave potential poisons to accumulate in an aquarium. If you think about it, even without fish or your fingers to liberate it, eventually that gas bubble will probably reach a sufficient volume that it works its way up through the sand/gravel and escapes into the water. And when it does, potentially a lot of poison is expelled. But wouldn't weekly sand mixing, or even mixing every-other-week, be frequent enough to prevent such a build up?

As others have pointed out, arguably this is probably not a problem with a tank if the substrate is only 1-2cm deep. But even in this circumstance, I observe the escape of (presumably harmful) gases when I lift driftwood or other decorations which cover the sand and deprive the substrate of normal water circulation and oxygen exposure. That's why currently I elect to get in there and stir up the gravel really well with each water change.

Cheers, Eric

[dw1305]

Hi all,

I too like the pre-filter design, but sometimes I don't have the time to maintain them, or my kids (who help me maintain some of our tanks) miss them, and as a consequence the filters clog occasionally. For that reason, I've started relying more and more on aeration mechanisms (like airstones or powerheads with venturis) which function independent of filter mechanisms. So far (knock on Repashy Morning Wood), I've never had an aeration systems clog, and when my pumps have clogged, I've not yet lost any fish in tanks which also had independent aeration systems. Contrast this to the disaster I had last January... .

I think that the additional power-head, or air stone, is a really good idea. I like "belt and braces", it avoids a single point of failure.

But it just doesn't seem wise to leave potential poisons to accumulate in an aquarium. If you think about it, even without fish or your fingers to liberate it, eventually that gas bubble will probably reach a sufficient volume that it works its way up through the sand/gravel and escapes into the water. And when it does, potentially a lot of poison is expelled. But wouldn't weekly sand mixing, or even mixing every-other-week, be frequent enough to prevent such a build up?

I'm not sure they will be that toxic, unless you have a lot of organic matter in your substrate the gases produced will be nitrogen (N2) and CO2, rather than methane (CH4) or hydrogen sulphide (H2S).

cheers Darrel

[bekateen]

I like "belt and braces", it avoids a single point of failure.

Actually, I think you taught me that, in my thread about deep gravel.

I'm not sure they will be that toxic, unless you have a lot of organic matter in your substrate the gases produced will be nitrogen (N2) and CO2, rather than methane (CH4) or hydrogen sulphide (H2S).

True, as long as CO2 and N2 are the only gases. I don't know whether my sand/gravel is dirtier than anybody else's, but I know baby ABNs make a lot of waste, and it feels like I can't keep up with them no matter how hard I try. LOL

[JamesFish]

In a week its unlikely much if anything would build up. Unless some really messy fish present and nothing cleaning up.

Personally I dont use deep substrate mines normally 1-3cm thick. This was advice given to me over 20 years ago and have kept to. It doesnt mean to say you cant but mines worked for me and thick enough for basic plants and ornaments.

In an 18x10 inch tank it has 0 issues the dwarf cory's keep it nicely does pack down a bit but never messy.
3ft well I had to take corys out as gets to much movement round the tank so does get debris build up and has dirty pockets that I try to clear up by shuffling a small section of sand at a time. Pumps are normally running at this point.

The smell of eggs is not always a bad thing I use some media that does produce that smell so yeah cleaning the filters really smells now the media is approaching end of life. Its hitting its year old mark but still continuing to work at reducing nitrates.

The media works by reducing flow through a packet and allows the bacteria required to form. Another company advertises media that does this as well if you can reduce the flow rate to 50L or less an hour.

On a side note I do remember watching a video on green machine that showed how to scape deeper and they did it by placing slate or a rock under the area you wanted to appear taller / deeper and pebbles infront to layer up on so this would give you some small deep area's but the bulk would be solid rock.

I have 1 tank running quartz gravel and has been for over a year with less than once a month cleans. I do however have a pump on it thats 2x the size needed.

I have MTS / killer snails in all tanks and giant vallis that quickly throws out new plants so it could be these are simply turning my over for me and the few pockets I do get are not causing an issue.

My khuli loaches never seem to bury themselves in sand but might be a useful edition to stirring the sand if you havent got anything that will eat them in a tank.

[TwoTankAmin]

Viktor Jarikov wrote:
Out of curiosity, would not the gunk be trapped in a mechanical prefilter, which is cleaned / switched frequently anyway, thus leaving the main filter unaffected?

Not really. A pre-filter should be a coarse sponge. Its job is to trap the larger particles. Because it must not impede the intake, it needs large pores. So two things should happen, the first is the smaller particles will go right through the pre-filter into the filter. The second is that those organics trapped in the pre-filter will be breaking down even between rinsings a week apart. When the organics get broken down it is not a process of "there one minute and gone the next," it is step like process where they become ever smaller. Some breakdown will happen in the pre-filter and some things will "let go" as a result.

Consider a basic hang on filter which has a proper pre-filter sponge on it. When you clean that pre-filter in a bucket of tank water, you will see some larger pieces let got. But then when you rinse the media inside, it's all much finer particles. I can only report that I have tried a variety of pre-filters over the years which are figgernt sizes and which had different levels of porosity. The finer the sponge, the faster it clogs. The primary function of a pre-filter is to reduce, not to prevent, the accumulation of waste in the internal media of a filter. Slowing the clog rate of the internal media reduces the chance that clogging will reduce or even curtail its efficiency in terms of flow through and providing oxygenation to the micro-organisms which inhabit that media.

Darrel wrote:
Again not every-one is going to agree, but I would very strongly recommend not using your filter as a syphon.

I do not think this is a good description of the mechanical filtration capacity of most filters. Consder how a bare bottom tank functions. There is no substrate to capture organic waste. So it cannot escape being in the water and thus it gets sucked into the filter. Unless a filter offers an extremely large volume of media, it will clog fairly fast. But with proper maintenance, it will do the required jobs and one can have a perfectly healthy tank without any substrate. Worried about single point falure? You can use multiple filters or use a filter with a larger media volume and a controllable flow rate.

As to how nature works to handle all these things, when are talking about in a tank, there are some major difference. The first thing to understand is that nature's "filters" are immense relative to those of a tank. For most of us, the volume of filter media is relatively small. Next, there are no gravel vacuums in nature or somebody to rinse out the sand/soil on the bottom and borders of water bodies. Finally, there is a much more diverse range of lifeforms involved which go well beyond the nitrifying bacteria/archaea. The best suggestion I can offer here is to refer you to a very well written article on the subject by Dr. Stephan Tanner on the Swiss Tropical site which you can find here http://www.swisstropicals.com/library/a ... iltration/

I am in the process of converting a number of my tanks to Matten Filters. They work more like how nature does than many other filters because of media volume and pore size control. These filters only need to be cleaned once every year or two. They also take a lot more time to establish fully. The nitrifiers are there as quickly as in more traditional filters, but the rest of what will eventually also colonize the foam takes longer. I have 2 tanks converted now for a number of months and I have not cleaned the foam, yet my water is perfectly clear. I still vacuum and I still change water as I have always done, but no media rinsing. Basically, the huge volume of media performs a lot of the same functions that having a deep substrate with plants does. It is not identical, but it works quite well, especially where plants are not possible.

The real key to understanding all of this is that all tanks are not the the same. They can't all have deep planted substrates for various reasons. Whether it is bare bottom breeding tanks, tanks with fish that rearrange the decor and substrate, tanks whose parameter are outside the range that supports plant life or they contain plant eating fish, they all need some form of filtration. They all have one feature in common, any filter becomes useless if it clogs. With traditional hang-on filters and a fully stocked tank, this can happen pretty rapidly and thus need frequent cleaning. When this is done, the essential nitrifiers can survive this but many of the other things that could be beneficial get removed. The result is one can have clean water in a tank with less media volume by doing regular manual maintenance. Use something like a Matten, with its immense volume, and the need to unclog it goes from weekly to annually or even bi-annually. What is ultimately living inside that huge foam and the processes that are active will be different from what will be in the much smaller filters. In these we have to clean the media to prevent clogging and, because this must be done often, there is no opportunity to develop the organisms that eventually colonize a deep gravel bed or a huge filter like a Matten.

The point here is there is more than one way to create a healthy tank in terms of filtration. The one thing all filters (including deep planted substrate which is essentially a "filter") must do is to deal with ammonia. After that the options are myriad and the choice of method needs to match the function of the tank. My bare bottom breeding tanks need to be just as healthy as darrel's deep bed planted ones. As the old saying goes,"There's more than one way to skin a cat."

I should mention I have all sorts of tanks- well planted with deep gravel. Well planted with no rooted plants (all ferns and anubias on wood and rocks), bare bottom breeding and grow out tanks as well as similar purposed tanks with shallow sand and neither plants nor lights. I have some fish that have been in my tanks for a decade+ (clown and sidthimunki loaches plus zebra plecos). And they are in tanks with different setups and filtration methods. A "good" tank should have the type of filtration and contents as well as a layout design which is appropriate for the specific inhabitants.

As always, just one man's opinion.

[Viktor Jarikov]

Interesting and educational. Gotta take a look at them Matten filters.

Viktor Jarikov wrote:
Out of curiosity, would not the gunk be trapped in a mechanical prefilter, which is cleaned / switched frequently anyway, thus leaving the main filter unaffected?

Not really. A pre-filter should be a coarse sponge. Its job is to trap the larger particles. Because it must not impede the intake, it needs large pores.

I'd think this may primarily apply to small(ish) tanks which use HOB's and canisters, and where there is no fail-safe = flow-around. I think without saying it I was thinking more about bigger tanks equipped with sumps where one can place the mechanical filtering of any porosity up to and including a polisher / aquasock before the bio filter and do it in such a way that if the mechanical part gets clogged up the water still flows over / around.

Besides, when one's using the mechanical stage for tank maintenance cleaning instead of vacuuming (btw, I think Darrel meant syphoning = vacuuming), they are present and observe the mechanical stage and also wring out the foams etc. right after the tank cleaning is done. Toward this procedure, a fine-pore prefilter can be put on the HOB or canister intake before the cleaning and removed / replaced with a large-pore one after.

I don't mean to oppose but to augment fwiw.

[TwoTankAmin]

It is not just for smaller tanks. Almost any site your read on the subject will say not to impeded intakes on pumps, canisters etc.

I agree re stirring substrate that this applies more to small tanks. However, it also applies to sumps. I worked with Dr. tanner to design the filtration for a sump for a 125 gal tank which I needed both to filter but also to add 25 gallons of water to the system. The sump will use only Poret foam. The layout is is a series of 3 inch thick sheets with one inch spaces between them. The first foam is a 10 ppi then next 3 are all 20 ppi and the final one is a 30 ppi. The end result is 15 inches of foam. The goal is not to have to clean any of these for a long time- think 1 to 2 years.

The gunk trapped in the first 10 ppi foam will be broken down into smaller particles which will continue to get smaller as they then move deeper into the system. The organic wastes form the basis for the food chain within the system. The one thing there will not be is any filter floss nor any real pre-filter except the sponge in the overflow which prevents anything dangerously large getting sucked through it. The primary difference between how a Matten style filter works and how more traditional filters work is with the latter we tend to remove mechanically trapped organics via rinsing. In the Matten they are degraded biologically and mostly become food for the organisms doing the actual filtration. Anything tiny enough to escape the filter system back into the water are removed via weekly water changes.

One of the best things about the Matten design is it becomes very easy to know when its finally time to clean the foam. When the water behind the foam is at a lower level than the water on the "tank" side of it, it's time to rinse it out.

[dw1305]

Hi all,

The problem with clogging the intake side of any "pump" is it can cause damage. One should always control flow on the output side unless you have a variable speed control that is a part of the pump or powerhead.

I agree with this, as you said earlier, the whole point of the pre-filter is that it is a large coarse (PPI10) sponge, and you clean it frequently, so that it doesn't impede water flow.

I have tanks where the filter sits beside, and just below, the tank, so there is very little head. This means that any constriction on the intake side leads to cavitation, and if this happens I know that the intake sponge (or hose) needs cleaning.

Besides, when one's using the mechanical stage for tank maintenance cleaning instead of vacuuming (btw, I think Darrel meant syphoning = vacuuming), they are present and observe the mechanical stage and also wring out the foams etc. right after the tank cleaning is done. Toward this procedure, a fine-pore prefilter can be put on the HOB or canister intake before the cleaning and removed / replaced with a large-pore one after.

Yes I do, sorry didn't really make it clear. What I don't want in the filter is any bulky organic debris. For example if you keep

Panaque

etc. you don't want the saw-dust and faeces in the filter. It's unsightly, but it isn't very polluting. I would syphon that out when I did a water change. In this particular scenario a tank with a very thin coarse sand substrate would be appropriate, other would say "bare bottom", but I'm not a conscientious enough tank cleaner for that to be an option for me.

If I do any major tank "spring cleaning" (with substrate disturbance) I rinse the intake sponges out before the clean, and also a couple of hours after the clean (when they will have acted as a mechanical filter). I don't see any problem with using a fine grade sponge to at this time, the problem for me would be forgetting I'd put it on.

I worked with Dr. tanner to design the filtration for a sump for a 125 gal tank which I needed both to filter but also to add 25 gallons of water to the system. The sump will use only Poret foam. The layout is is a series of 3 inch thick sheets with one inch spaces between them. The first foam is a 10 ppi then next 3 are all 20 ppi and the final one is a 30 ppi. The end result is 15 inches of foam. The goal is not to have to clean any of these for a long time- think 1 to 2 years.

The gunk trapped in the first 10 ppi foam will be broken down into smaller particles which will continue to get smaller as they then move deeper into the system. The organic wastes form the basis for the food chain within the system. The one thing there will not be is any filter floss nor any real pre-filter except the sponge in the overflow which prevents anything dangerously large getting sucked through it. The primary difference between how a Matten style filter works and how more traditional filters work is with the latter we tend to remove mechanically trapped organics via rinsing. In the Matten they are degraded biologically and mostly become food for the organisms doing the actual filtration. Anything tiny enough to escape the filter system back into the water are removed via weekly water changes.

One of the best things about the Matten design is it becomes very easy to know when its finally time to clean the foam. When the water behind the foam is at a lower level than the water on the "tank" side of it, it's time to rinse it out

I'm a great fan of HMFs as well <http://www.planetcatfish.com/forum/view ... er#p284569>, what it does is replicates the ecological processes in the top few centimetres of a porous substrate. Especially if you don't have a substrate, then that is a really good idea.

The description is on Dr Tanner's site, the link you posted earlier <http://www.swisstropicals.com/library/a ... iltration/> and also the HMF link <http://www.swisstropicals.com/library/mattenfilter/>, and you can see them in use at <http://www.brianstropicals.com/pages/My-basement.html>.

Like Stephan, Brian is a professional scientist and hobby aquarist.

cheers Darrel

[JamesFish]

Okay this is proving an interesting read for me atleast.

Lets see if my basic understanding is right.

The traditional basic tank guide is
fish waste into substrate and filter > breaks down or trapped.
Filter is cleaned in tank water and nitrates removed by waterchange. Substrate is cleaned by gravel cleaner or stir / siphon up the waste.

Deep gravel
Attempts to trap and allow bacteria to form to break it down. The low flow is supposed to allow de nitrafiying bacteria to form and allow it to reduce nitrates in the tank. This should form bacteria / micro organisms in the deeper slower flow sections of the substrate. By stirring it early or movements release gas build up and this can be toxic.

External filter + JBL bio media
Has worked for me for a year now does have some side effects other things drop on the nutriant side. Plant life requires an occasional fert adding to prevent bad leaves forming. The once a month water changes appear to lack a few nutriants after a while. Fish dont appear to be harmed or ill due to this but still early days.

HMF - Filters
Work by building up the same bacteria / organisms that deep gravel does?
Large media area, the filter builds up gunk over time providing a breeding ground for everything needed at all areas. The huge volume of surface area and as flow slows in area assume it allows the eco system to form to deal with it all.

Bacteria
My understanding is often these depend on each other. Now I know the normal cycle takes about a month to kick in on a typical filter and the extra media takes 6 weeks ontop to fire up.

I assume its the same if not longer for deep gravel and the HMF to build the bacteria / debris layers required.

Tank Size
Not sure how much this changes things. Larger tanks are obviously going to be more tolerant of changes and have large surface area's. Small tanks often have a small surface area but the % is something of a headache to workout so wont try.

Substrate cleaning
On long left tanks this is often suggested to do in sections. Now this is largely said to be to avoid changing the environment to much. But on deep substrate this would also destroy the bacteria people are seeking to cultivate in some areas. Some have just said leave it and let it do what it wants. Yet frequently people state dirty substrate as a cause of bad barbel infection. I think the barbel has to cut itself first so perhaps it should be sharp and dirty substrate.

It could just be if you have nothing throwing the substrate around or digging in it than leaving to do what it wants is fine as any gas escapes would be small?

Traditional view is clean once a month or vaccum weekly. Depending who you ask.

Now from the above it seems that your tank size, stocking, type of substrate and filter all impact your ability to use tank maintenance. By this I mean that if you have big fish that throw the substrate round how they want you can't cultivate the bacteria always. Larger tanks I guess are also harder to clean well frequently as amount of water you remove in process or time it takes. This might be why the HMF is coming in as its doing allot of work for you. On a small tank I might give this a try as its not pretty by looks of it but if you can get it working for you looks great. I'm really excited by it as potentially it could be an end to frequent prefilter cleans, monthly canister cleaning and substrate cleaning down.

Little bit of an old style setup but worth a mention
This one isnt mine but a layer of 2-3 inch thick peat with a mesh gravel guard covered by quartz and with plants its keeping a pretty low nitrate reading and you can see the gasses escaping under the substrate.

Now which bit did i mess up or miss understand?

I would also like to learn more about the bacteria / organisms used to break down and the habbitats they like to live in. Please english ones I dont ussually understand the technical sheets of information. Sorry some papers are really contain to many big words for me.

[dw1305]

Hi all,
James I think your summary is pretty much right, but it also indicates why it is easy to lose your way in the tangle of conflicting advice.

A mature HMF is fulfilling the role of both filter and substrate. It has the advantage over the substrate of being vertical, with its top exposed to atmospheric oxygen. There is nothing to stop you planting the top and tank side face (a lot of plants grow really well on them).



There isn't a single right answer to biological filtration, and if you review this thread and "Deep gravel..... (http://www.planetcatfish.com/forum/view ... =4&t=41038) etc. you will see a lot of different opinions.

It isn't a very exciting approach, but my suggestion to people is to use a "risk management" approach to fish welfare. The single greatest risk to fish health is low levels of dissolved oxygen. The reason for this is that any period of time, however short, when oxygen levels are below the requirement for any particular fish will lead to its death.

Because of the paramount importance of maintaining dissolved oxygen levels I like 2 filters, a reasonably fine and undisturbed substrate (usually sand), plants (including those with access to aerial CO2 & oxygen), MTS, a lot of water turn-over, regular water changes, light stocking and a large gas exchange surface area. They give you stability and resilience, there isn't a single point of failure and any changes are going to occur fairly slowly, giving you time to react.

Things I don't want are anaerobic de-nitrification (microbial conversion of NO3 to N2 gas) occurring in the filter (HMF are an exception, although I don't mind if all the HMF media remains aerobic).

It is quite possible to have a fine porous media in the filter, but you run the risk of catastrophic de-oxygenation occurring. It is back to risk management, it is a very serious risk, so why have it if you can avoid it? You can remove nitrates with water changes and plants (my preferred option), or by de-nitrification in a "deep sand bed" (or undisturbed substrate) or by ion exchange resin, you don't need it to happen in the filter.

The substrate will naturally have fluctuating zones of oxygenation, I see that as a good thing. Plants nutrients will become available under reducing conditions (zones with low oxygen levels or negative REDOX potentials) etc.

cheers Darrel

[bekateen]

The challenge I face when trying to realize success with all the options listed above is specifically with the plants - most of my tanks are planted, but the plants don't thrive (the exceptions are Java moss and Java ferns - they do pretty well). My experiment with a deep gravel planted tank didn't prove successful (probably for many reasons, LOL), in part because my plants never took off and flourished. I'm sure there are several reasons for this (micronutrients, CO2, etc), but no matter. As you say there are several ways to achieve good tank conditions, so currently I simply choose to work within the boundaries I find success with. But there are definitely areas I'd like to improve in with regards to tank and filtration setups for more reliably and consistently clean water quality.

Darrel, I'm curious about your photo - What supports the plants shown in your picture? Are they merely floating on the water surface? Are they planted in the tank substrate and growing up through the water column? Are they on floating supports (e.g., foam blocks) or anchored along the side walls of the tank? Or suspended on a base above the water?

Thanks, Eric

[bekateen]

I am in the process of converting a number of my tanks to Matten Filters.

TTA, Darrel, and anyone else with experience using H-M filters, I have a shopping question for you (I know this is off topic for this thread about stirring sand/gravel, but I'm the OP so I don't mind ):

I too have wanted to try using H-M filters for a long time, but they are so "alternative" in my mind that I've never taken the leap. And nobody I've met in person seems to use them. I'm looking at the Swiss Tropicals website where I want to buy a H-M filter with a JetLifter for my 20Gal High aquarium. Here are the options they offer for this sized tank:

What PPI do you think is best? This tank is currently housing just my oil cats and a few golden tetras, and eventually it will house my mustard spot plecos (

Panaqolus albomaculatus

, more about them here: Mustard spot pleco (Panaqolus albomaculatus) project), so a very woody mess will be made by these guys. Would you recommend the coarser foam (10 PPI) because of the woody poop of the Panaqolus? Or does the type of pleco not affect my decision process here? I'm not asking this in order to avoid vacuuming up fish poop, but I expect that some of the woody fish poop will be sucked into the foam no matter how well I vacuum, and so I don't want the foam to clog.

Also, what do you recommend for an airpump to drive this thing? I'm really at a loss for what size air pump to buy to power a JetLifter for a 20Gal High tank. The pump recommendations on the Swiss Tropicals website seem to lean towards really powerful pumps meant to drive multiple tanks at once, but I'd be using this pump for just this one tank.

Any recommendations would be greatly appreciated.

Cheers, Eric

[bekateen]

P.S. @swisstropicals, please feel free to respond here too. Thank you.

Cheers, Eric

[TwoTankAmin]

In my 20 long I have a 2 inch thick 20 ppi. In the 33 long its 3 inches thick and also 20 ppi. Both tanks are bare bottom.

I also use a number of the Poret cubes. I have one 3x3 30 ppi in a fry grow tank with one 4x3 20 ppi, eight more 4x4 20 ppi in various tanks and then two 5x5 20 ppi. These work very similar to Mattens but on a smaller scale. I only tend to rinse every 3 -4 weeks.

Basically, I was told a few things by Dr Tanner in terms of how to choose porosity.

1. More pores pers inch, the sooner they clog, relatively speaking.
2. The fewer the ppi, the higher the flow one can have but 10 ppi will not do as good a job as the higher ppis.
3. Most of those non fry/shrimp oriented Poret sizes suggested on the site and by Dr. T to me are 20 ppi. In multiple sheet use, one can start lower and end higher, but 20 ppi seems to be what does the job well and will clog the slowest. Especially when it is a one sheet tank.

I came up with a design concept for use in pleco breeding tanks which I also ran by him and as a result am about to try. Normally, one can use either an air powered jet lifter or a return pump and hose. I use the latter in the 33 as I want maximum potential aeration via surface agitation. I even built a custom spray bar for the return. But I also want to have a current blowing across the bottom of the tank. So I have a second smaller pump at the opposite end which pushes water towards the Mattern.

My idea was, instead of the above, to use a pair of 2 inch Poret sheets, one on each end of the tank and both powered by small pumps. One return would come over the top, but from the 2nd foam the return would come out through a hole drilled in the foam close to the bottom glass. The result should essentially be a circular flow pattern in the tank. This takes up more space but it also increases the total media capacity by 33% over a single 3 inch foam. I have yet to set this up but I have all the needed parts.

I also have a few canisters not yet put into use that will be filled 100% with Poret, and no floss. The dual basket ones get 20 ppi in both baskets. The one with 3 baskets will have 10 ppi in the first and 20 ppi in the next two.

Almost all the sizes I am using were chosen after I asked Dr. tanner what he recommended for each tank/sump/canister.

This is an entirely different approach to filtration than I had used for almost 13 years. All the work is being done biologically. It is really nice, but still a bit disturbing, to clean a tank simply by vacuuming it, sucking out more water and then refilling it. I have used multiple filters on tanks for years and cleaned them every week.

The other change, and why I needed extra current in pleco tanks, is that Matten filters should have a slower flow through. Slower than most traditional filters use. The sump I described using a 10 ppi, 3 x 20 ppis and 1 300 ppi was to hold 25 or so gallons of water and be used on a 125 gal. tank housing larger clown loaches and other fish. The suggest return flow rate for that set-up was suggested as follows: "I would pump only about 400-500 gal/h." So any additional flow or circulation I want will come from other equipment.

I hope this helps and that Dr. T. chimes in to correct anything I might have gotten wrong as well as to contribute his expert knowledge on this subject.

@eric- As for the woody residue. Big pieces that reach it should stick to the foam so when you vac the tank, suck them off? Smaller piece that might go in will break down and be dealt with accordingly. The thing about that big thick sheet of foam, is that it is not easy to clog. That is why there is that 1 -2 year time frame between cleanings. Since mine are only running about 5-6 months, I have not reached that point. 20 gallons is a small tank with a huge foam. Consider how much media you would have in almost any filter suggested for even a 30 gal. tank. However, my experience suggests the wood will end up on the bottom to be sucked from there and not on/in the Matten

[dw1305]

Hi all,

Darrel, I'm curious about your photo - What supports the plants shown in your picture? Are they merely floating on the water surface? Are they planted in the tank substrate and growing up through the water column? Are they on floating supports (e.g., foam blocks) or anchored along the side walls of the tank? Or suspended on a base above the water?

They are growing on top of the HMF filter sponge.

cheers Darrel

[bekateen]

Thanks TTA for the info on how you set up your HMF. I think I'll start with a basic, simple filter, but I like the idea of yours to have two filters, one at each end and one with a return at the bottom instead of top.

So it sounds like 20PPI foam (2" thick, since that is what Swiss Tropicals offers) is sufficient for a 20Gal High tank.

As for the woody residue. Big pieces that reach it should stick to the foam so when you vac the tank, suck them off? ... my experience suggests the wood will end up on the bottom to be sucked from there and not on/in the Matten

Okay, that's what I would hope too.

By the way, I realize that the @ mentions function is a new thing and we need to get used to it, but TTA, FYI it only works with website usernames, not real names. You typed the @ symbol followed by my real name, so I'm not going to receive any notification of that mention. Instead, you sent a notification to another person whose PlanetCatfish username actually is "Eric." But no matter, I read your post and saw the @ mention symbol, so I got the message.

They are growing on top of the HMF filter sponge.

Okay, thank you Darrel. Following up on this, if I allow plants to grow on a HMF sponge, do the plant roots clog the filter? And is it bad if the plants start to grow on the side of the filter opposite the main volume of the tank (I.e., up against the glass, near the return tube)?

And again, sorry to be repetitive, but I'm having a hard time envisioning what kind of air pump to use to drive this - TTA, you mentioned that HMF need a slower water flow than other conventional filters, I presume so that the bacteria have more time to work, so to speak.

If I go with a typical air pump, the brands available in my local stores are Aqueon, Fluval, Tetra, Marina, Fusion, and Coralife (and maybe a few more. If I'm setting up this HMF to clean a 20Gal H tank, what "tank rating" should I look for? My inclination would be to select an airpump which is rated for an aquarium size about 40-100 gallons (e.g., the Tetra Whisper 40, or 60, or 100). Is slower better? If I took the water pump approach, I already own an Aqueon QuietFlow Submersible Utility Pump 800 (Model AQ800), which has an adjustable water flow rating of 80 to 211 gph. But would a water-flow pump be vulnerable to clogging, if located behind the HMF? Obviously an air line won't clog.

Keep in mind that the HMF water flow is not the only flow in the tank. I also have an Aquaclear Powerhead 70 with an airline acting as an aerator/circulator.

Thanks, Eric