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Flow through fry tank design
Posted: 26 Jan 2005, 07:34
by Barbie
A friend that works with acrylic came into the store the other day, and I was asking him about making a flow through container of some type to hold different sizes of fry without having to use different sources of water flowing through. Then I can use one battery backup powered air pump that kicks on when the power goes out. Yes, I know it's not a generator, but I'm working on that!
He got right on the project, and brought it into the store today. I am VERY happy with it! The water flows over the first chamber from an air powered sponge filter, then each divider has a hole in it that I insert a large pore sponge over. This allows the water to flow through each of the chambers freely, but the fish can't. The bottom 3 inches is solid, so food can settle in each compartment. I just use a turkey baster to remove any waste. Here are a few pictures. Input is definitely welcome! (only two of the chambers are full in these pics, the rest are left to free flow for demonstration).
Barbie
Posted: 26 Jan 2005, 11:26
by sidguppy
a big THANK YOU for posting this;
now I can get creative with the scenario; a pencil and paper, glass and a glasscutter, a lot of silicone-glue and baby catfish
Excellent job btw, you can pass the congrats.
Re: Flow through fry tank design
Posted: 26 Jan 2005, 11:42
by coelacanth
Barbie wrote: He got right on the project, and brought it into the store today. I am VERY happy with it! The water flows over the first chamber from an air powered sponge filter, then each divider has a hole in it that I insert a large pore sponge over. This allows the water to flow through each of the chambers freely, but the fish can't. The bottom 3 inches is solid, so food can settle in each compartment. I just use a turkey baster to remove any waste. Here are a few pictures. Input is definitely welcome! (only two of the chambers are full in these pics, the rest are left to free flow for demonstration)
Watch your dissolved oxygen levels in the later compartments. Assuming you leave the sponges in place for more than a few days, you will get aerobic nitrification taking place which can significantly drop DO levels with only a single inflow. You could find the cumulative effect enough to affect growth and survival. You can get around this by washing out the sponges every couple of days under tap water, or having an "trickling" air stone in each compartment (if you have it on low enough you will get adequate circulation without putting the food into suspension).
Posted: 26 Jan 2005, 13:39
by Shane
Barbie,
Great idea! My only suggestion might be to remove the fry raising tank altogether from the parent tank and use the parent tank as a "sump." That way you could preform water changes in the main tank without bothering the fry. As I see it now (maybe you have already solved this) the fry will be left high and dry during a water change in the main tank.
-Shane
Posted: 26 Jan 2005, 14:09
by Caol_ila
Hi!
A german guy has been selling a similar thing on ebay for a while.
http://www.aquarienbastelei.de/behaelter.htm
Posted: 26 Jan 2005, 16:56
by Barbie
The sponges get rinsed every day or two if there's any food at all in them, or a rise in the water level due to reduced flow. I figured DO will be my limiting factor, but this tank is super oxygenated with about 15 times the actual volume turnover an hour with a full venturi running, also. If I notice the fry acting stressed, I can add a spraybar pretty easily, I'm just trying to find something I can use a battery powered air pump on as a backup. They're a wee bit cheaper than a generator at this point, and I've been having nightmares and what not about power outages ;).
The fry tank only has slits that go down about 2 inches into the box. I realize it's hard to see in the water. It literally hangs over the side of the tank, with acrylic legs to keep it level. So when I do water changes, the water will always stay 3 inches or more in the box.
I was just brainstorming when I asked the guy if he could build something like this, but he did a bang up job on it. I have had quite a few individual containers holding fry kicking around. This will let me consolidate them at least. The sponges used between containers is a large pore aquaclear filter sponge. I just cut it to fit the slots. It really doesn't reduce the flow by much, and you'd be amazed how much water one of those little sponge filters can put out with a high rated air pump, hehe. The spray bar like on those individual boxes was my only considered addition, and it may end up being necessary. I just had very little luck trying to run one with an air pump and I REALLY want a back up plan, without having to go buy a battery backup for computers for the tank. I guess that will probably be my next option though.
Just thought I'd share the design. 
I know there are a few potential problems with the flow, but it's definitely worth figuring that out for the convenience. No more having the guppies eat all the Apisto. cacautoides free swimmers and having my hubby all irritated! ;) The guy said he could make more of them for 30 bucks, so if anyone wants them I can forward you to him.
Barbie
Posted: 26 Jan 2005, 17:51
by Kenneth Wong
Hi barbie,
This is what I do for backup power in all my tanks. I use a regular air pump(tetra luft) plugged into a UPS backup. I have experimented with these pumps and have found it to last around 4 to 5 hours on a 350VA UPS. I got my cheap UPS at FRYS electronic when they have their sales. All my tanks have at least an airstone and a sponge filter along with the regular filtration for this very reason.
Ken