High pH causing confusion

[ILikeFish]

Hi, 

I’m in charge of a commercial fish system at work. These systems run auto water changers, UV sterilizers, etc. the water also goes through a water softener prior to entering the tanks. Out of the tap, the water is between 7.4 and 7.6. After 24 hours in the tanks, it climbs all the way to 8.2 or higher. 

Just this morning, I tested ph at 8.2 and kH at 10dkh. I am curious if anybody had any idea what could be causing this. It is impacting our livestock with higher than normal mortality rates.

I haven’t tried any chemical solutions yet, but I’d consider anything at this point.

Any help would be much appreciated

[Wrencher_Scott]

On 4/24/2022 at 9:23 AM, ILikeFish said:

Hi, 

I’m in charge of a commercial fish system at work. These systems run auto water changers, UV sterilizers, etc. the water also goes through a water softener prior to entering the tanks. Out of the tap, the water is between 7.4 and 7.6. After 24 hours in the tanks, it climbs all the way to 8.2 or higher. 

Just this morning, I tested ph at 8.2 and kH at 10dkh. I am curious if anybody had any idea what could be causing this. It is impacting our livestock with higher than normal mortality rates.

I haven’t tried any chemical solutions yet, but I’d consider anything at this point.

Any help would be much appreciated

I'm assuming you are talking only freshwater cause you mentioned auto water changers.

All fish are good at 8.2 and the kH doesn't matter. Also PH can swing big time during the day.

I would question the test you use, they are notoriously inaccurate. I think you are barking up the wrong tree here anyway. 

What do you use for aeration? What about tap water chlorine removal? If you have carbon filter on the tap water they don't last forever. UV lamps don't last either. 

My first thought would be biofiltering if all else is working (mainly chlorine and chloramine removal), is there enough, is part of the system not working? Is it setup with sumps? 

How about temps? it's not that important but extremes are bad of course. 78 F would be a great temp for a large system and most all fish. 

Edited April 24, 2022 by Wrencher_Scott

[modified lung]

Your water probably has a CO2 problem. It's coming in from the tap at somewhere between 9–14 mg/L (2k–3k% saturation) and degassing over night to 2 mg/L (400-500% saturation, normal) which is why the pH raises.

That's usually not enough CO2 to kill fish so there's probably multiple chronic problems stacking on each other if you're seeing mortality. If there's high levels of CO2 coming in, there might be other things coming in with it that causing the mortality instead.

What are your other parameters? Are you using groundwater? Does your facility have a degassing tower or tank? Do you have a TGP meter? What kind of fish? Have you seen any redness or burst capillaries on your fish?

[Wrencher_Scott]

If that is the case there is another reason for good aeration. 

I have a feeling we will not here from the OP again anyway.... 

[ILikeFish]

On 4/24/2022 at 2:21 PM, modified lung said:

Your water probably has a CO2 problem. It's coming in from the tap at somewhere between 9–14 mg/L (2k–3k% saturation) and degassing over night to 2 mg/L (400-500% saturation, normal) which is why the pH raises.

That's usually not enough CO2 to kill fish so there's probably multiple chronic problems stacking on each other if you're seeing mortality. If there's high levels of CO2 coming in, there might be other things coming in with it that causing the mortality instead.

What are your other parameters? Are you using groundwater? Does your facility have a degassing tower or tank? Do you have a TGP meter? What kind of fish? Have you seen any redness or burst capillaries on your fish?

Thanks for the reply. 

There isnt any CO2 being injected into the tanks. Other parameters are 

Ammonia: 0

Nitrite: 0 

Nitrate: 0 

Chlorine: 0 ( as tested by tetra test strips) 

Water comes in from the tap from the city. There is no degassing tower or tank. I don't notice any redness or burst capillaries, however from time to time I do notice some drooping tails. 

I am not sure what a TGP meter is. 

On 4/24/2022 at 1:23 PM, Wrencher_Scott said:

I'm assuming you are talking only freshwater cause you mentioned auto water changers.

All fish are good at 8.2 and the kH doesn't matter. Also PH can swing big time during the day.

I would question the test you use, they are notoriously inaccurate. I think you are barking up the wrong tree here anyway. 

What do you use for aeration? What about tap water chlorine removal? If you have carbon filter on the tap water they don't last forever. UV lamps don't last either. 

My first thought would be biofiltering if all else is working (mainly chlorine and chloramine removal), is there enough, is part of the system not working? Is it setup with sumps? 

How about temps? it's not that important but extremes are bad of course. 78 F would be a great temp for a large system and most all fish. 

Yes, the tanks are freshwater. I agree that the ph at 8.2 isn't necessarily a problem but a symptom of a bigger issue. As far as aeration, we do not do anything special there, tap water chlorine is removed via degassing in the sump prior to being pumped up into the tanks. We change the carbon filters once monthly and the UV lamps get changed 2 times a year, every 6 months. Specifically, the tanks are Marineland commercial systems. We do a constant temp of 76 across the board. I find that hardier fish are able to survive, however most tetras, mollies, etc. are not doing as well. I have variatus and zebra danios that have currently been living in there for about a month. African cichlids are also loving it

[ILikeFish]

Update, 

 

I purchased a liquid test for chlorine and tested the tanks, the test I bought, a pool test, was not able to detect any chlorine in the system. I am still open to the idea of that being the problem, but I am not sure thats exactly what our issue is. It aeration makes sense that it would be an issue, I will see about adding air stones to the sumps to increase oxygen content in the tanks. Will report back with any updates.

[modified lung]

On 4/25/2022 at 10:14 AM, ILikeFish said:

There isnt any CO2 being injected into the tanks. Other parameters are 

You misunderstood this part. I wasn't say you're injecting CO2 into the tanks. CO2 comes in with groundwater and city water and sometimes at high levels. The tap water at my house for example comes out with ~10 ppm CO2 already in it. That's why your pH is changing over night.

Droopy tail is a sign of low oxygen. This could be the main issue. Low oxygen makes the chronic toxicity level of almost every water quality parameter worse to fish. Increasing aeration would fix both a high CO2 and low O2 problem.

TGP means total gas pressure. You probably don't have to worry about this with city water except maybe as a last resort.

[Torrey]

On 4/24/2022 at 10:23 AM, ILikeFish said:

Hi, 

I’m in charge of a commercial fish system at work. These systems run auto water changers, UV sterilizers, etc. the water also goes through a water softener prior to entering the tanks. Out of the tap, the water is between 7.4 and 7.6. After 24 hours in the tanks, it climbs all the way to 8.2 or higher. 

Just this morning, I tested ph at 8.2 and kH at 10dkh. I am curious if anybody had any idea what could be causing this. It is impacting our livestock with higher than normal mortality rates.

I haven’t tried any chemical solutions yet, but I’d consider anything at this point.

Any help would be much appreciated

I second ModifiedLung with something in the tap water side. This Helps explain how tap water can end up with CO2 and why it would be a problem... or at least a concern.

Also, do you know why  they softening the water? Most water softeners use salts, which will not be healthy for plants or fish..... and will add to the complexity of you identifying the problem.

 

[Wrencher_Scott]

On 4/25/2022 at 10:14 AM, ILikeFish said:

Thanks for the reply. 

There isnt any CO2 being injected into the tanks. Other parameters are 

Ammonia: 0

Nitrite: 0 

Nitrate: 0 

Chlorine: 0 ( as tested by tetra test strips) 

Water comes in from the tap from the city. There is no degassing tower or tank. I don't notice any redness or burst capillaries, however from time to time I do notice some drooping tails. 

I am not sure what a TGP meter is. 

Yes, the tanks are freshwater. I agree that the ph at 8.2 isn't necessarily a problem but a symptom of a bigger issue. As far as aeration, we do not do anything special there, tap water chlorine is removed via degassing in the sump prior to being pumped up into the tanks. We change the carbon filters once monthly and the UV lamps get changed 2 times a year, every 6 months. Specifically, the tanks are Marineland commercial systems. We do a constant temp of 76 across the board. I find that hardier fish are able to survive, however most tetras, mollies, etc. are not doing as well. I have variatus and zebra danios that have currently been living in there for about a month. African cichlids are also loving it

Those sound like what they use at Petco. Do you do much water changing? I know they auto refill but I believe you must remove water (it's not 100% auto). I would be curious what the TDS is, it could be that over the years they have not been changed enough to keep the water from getting extremely hard because of evaporation. As for aeration I don't think that's it because those have biowheels correct? With lots of salts in the water (hardness) comes lots of harmful bacteria and high ph