High pH

[CommonPl*co]

Warning - long on detail, because I suspect most of these answers will be questioned otherwise.

I have a hatchery of about 10,000 gallons (mostly 29s) and 17 years of experience in the hobby. This isn't a simple "Are you overfeeding?" type of issue. I can normally provide the answers, but not this time.

Tanks are divided into 16 rows of tanks, individual tanks connected on a row with PVC tubing. All are running off of sponge filters. All get at least 50% water changes at least once a week. Most get 50% twice a week with another smaller, 20-30% sometime. Discus section gets 50% at least 5X/week.

pH is tested with digital Hanna Checker, spot confirmed by Red Sea test. South American import section has pH of 7.4, thanks to half of water changes with RO and early dose of muriatic acid to start it well below 7. The rest of the hatchery is running at 8.5. (Discus get RO as well, and are at 8.3. I had discus breeding in 8.3 water yesterday! I don't expect success there.)

Tap is 7.5. Common elements from section to section are water supply, food, and air supply. Tested water through refill system to be sure nothing was coming from the hose/plumbing - 7.5. Tested food by placing some in jars for a few hours - 7.5. Have a theory about the air possibly being the culprit.

Jars (to pull angel eggs) that were tap hit 8.5 in under a week. (I just discovered the problem yesterday, so don't have running data available - yet!) That places the problem clearly with the source water itself or the air. The brine water I have mixed up nearby is not aerated, and has a pH of 8.0, lower than salt water because it is made with rock salt, not salt mix. Yet it is still lower than all the areated water everywhere except the S.A. imports. All the RO and acid adjustments still not being very effective have me stumped.

My blower is located in the closet with the water heater. (I call it the "water closet" ) It is not ventilated. My first thought was carbon dioxide, but CO2 should drop the pH, not raise it. Next was gas - but my hatchery is all electric, no gas anywhere. I've been talked out of this, but can't see water alone being responsible for 8.5 pH. Will just plumbing the air filter out into the hatchery itself resolve whatever issues may exist here?

The other possibility I've thought of is still the tap water. If our water supply is normally really high in pH, and is being artificially lowered, then any aeration could naturally raise it back up. But 8.5? I've never heard of anyone having a pH that high. I'm working on an automated system, and will be filtering all incoming water. If the water is the problem, is there anything out there that can help this besides RO? Will a 5 micron pre- be enough, (then, of course, a carbon block to strip chloramines et al) or will I need to follow it with a smaller post-filter?

Oh, and ammonia is 0, nitrite is 0.1, and nitrate is 1 ppm, nitrites higher than they should be with active sponges and regular large water changes, but not surprising considering how screwed up the pH is. Don't have hardness tests, but I know it is very high. (Okay, yes I'm overfeeding a bit, but I'm trying to grow out fish for a living. It is a controlled, barely-overfeeding and siphoned up soon afterwards. Deal with it. )

Ideas?

--Jim

[Shane]

Jim,
Thanks for laying out all the facts. I highly doubt it is your air system. I would check the following issues in your shoes. They will alll require a call to the County or City Water Department.

1) Has the city changed their water supplier? You may have been getting softer more acidic (not that 7.5 is acidic) water from a different river or resevoir.

2) Has the city "flushed" their pipes with some chemical high in salts? Have they started adding minerals (like flouride)?

3) Does the city run a "water softener" system that is down (or due) for maintenance?

With the type of set up you have, I would install some inline filters for the mains going to the hatchery. Several companies offer activated carbon and mechanical filters that contect to your water mains. These will also keep your RO systems running longer as there will be less stress on them.
-Shane

[CommonPl*co]

Thanks, Shane. Whatever they've done, I have an issue that needs resolving. I'm planning on a "whole house" filter already, but will a 5 micron pre and a carbon block filter get the job done? If not, what more do I need?

[Shane]

Short of drilling your own well, I am not sure what more you could do.
-Shane

[Janne]

I agree with Shane, it sounds like your water supplier have change something in their production of tapwater. They maybe have start or increased the use NaOH sodium hydroxide to stabilize the pH at a high level and depending on the method they use to make chloramine it can hold a small amount of H2CO3 carbonic acid that dissapear from your water easily when using air driven filters, I am just speculating but that can explain why your pH increase. Carbon filter take chlorine but not chloramines.

Janne

[Durlänger]

It`s not only the water supplier some comes from CO2
Stop with pulling CO2 in

1. pH1-6 : All inpulled CO2 will still be CO2, less KH
2. pH7-8 : Most inpulled CO2 will become H2CO3 but still a
bit CO2, middle KH
3. pH9-14 : All impulled CO2 will become Na2CO3, K2CO3,CaCO3
and MgCO3, that thing`s are those which KH and GH
are depending on , so much hardness.

With pH8,5 your tank`s are between 1. and 2. so your CO2
will become mainly H2CO3, Na2CO3, K2CO3,CaCO3
and MgCO3, and very, very, very less CO2

You may don`t overfeed as you thought as you said your hardness comes mainly from the CO2

To bring pH and KH down you should use black peat
It will take some-much time becouse of your hardness so you also have a look at the citywater (ph, KH and GH) may you let these water first through black peat before you use it in you tank`s
As soon your pH is near 7 you should look at the CO2 level, becouse it will get much higher (H2CO3 CO2 + H2O):!:

[racoll]

I think you answered this, but those digital pH meters can drift very quickly.

When was the last time you calibrated it?

Is the calibration fluid fresh?

[bronzefry]

Shane is absolutely correct. I've also seen the level of disclosure required vary from municipality to municipality. Some areas are required to inform you if any substance is added to your water or if any odd substance is found in the water through regular testing. Other areas aren't required to tell you anything. Several areas in the US have a drought. If you're in one of those areas, I'm wondering if this could impact your water. As Shane stated, the supplier of the water is important. Well water, resevoir or a treatment plant are all common sources in your area.
Amanda

[CommonPl*co]

Racoll - I hadn't answered the part about my meter - but I had newly opened packs of fluid and calibrated just before testing.

Durlanger - Sounds like you know CO2 and pH well. I don't understand completely, though. We most often are told that CO2 drops the pH, but if I'm understanding you correctly, you're saying that at my high pH the CO2 is just converted to something else and doesn't actually affect the pH? I'm not actually adding any CO2 deliberately anyway, but may be inadvertantly from the closed water closet. I'm working on airing the whole place better anyway through the heat of summer.

Janne - I've always heard that carbon only pulls the chlorine, too, but I've seen otherwise. Most of the pet stores where I'm familiar with their workings use a large carbon tank as the only water treatment they use for most of their freshwater tanks - so it is pulling the chloramines as well. I have a spigot already in place after only the carbon tank on my water softener at home that I don't actually use; I'll go check it this afternoon for myself. If it doesn't, my whole automation plan is shot. Don't have the capital to dig a well just yet.

Thanks for the input, everyone.

--Jim

[Durlänger]

You have understand me well. The firm`s which shell CO2-Equpment normaly say that it will keep pH at a good pH, they don`t say it will make a good pH. I also sayed that your hardness is going to get harder if you would put CO2 in.

Also I sayed that black peat will bring pH and hardness lower

With "carbon" you mean Na2CO3/K2CO3 or a matrial similar to concrete or what we German call "Kieselgur" (the thing used in external filter`s with the macro-holes)

Can you calibrate the temp. on your pH-meter, too? Can you also have a look at the µs with it? I ask that because that would tell me a bit if your meter is a good (for chem. industriall) or a "cheap" (from petshop) one