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Tilapia dying after PH spike

I am also a Aquaponics newbie. I read Sylvia's book and dove in last October. Everything was great until a couple weeks ago when I expanded my system. I added a 3'x5' DWT to my system which is a 55 gal plastic Barrel for the tank, one cut in half for 2 media beds and another half barrel for a sump. I had been testing my water weekly and not had to make any adjustments for weeks and totally forgot to check the PH of the water I was adding to the system. I noticed the fish acting funny but didn't get around to investigating deep enough to find the PH over 8 until a couple days later. It took me a week to get it back to 7 as the two bottles of the cheep PH down I was using from the pet store didn't do the tick and had to order some online. I lost several fish initially.

Now a week and a half after stabilization, I am still losing a fish here and there. They are not eating and are still very lethargic and some are floating funny. I have checked all the other basics like ammonia and Nitrites and all are good. Have I permanently damaged them all or will they recover? Any tips?

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Replies to This Discussion

Permalink Reply by Jack Dunbar on January 12, 2015 at 4:27pm

Hi David. You want to gradually change your PH. I don't believe a PH of 8 would've killed them. You didn't mention the temp?

Permalink Reply by David Langham on January 12, 2015 at 5:46pm

The system is inside. I also have a water heater. It stays a steady 75. The API test kit was showing fairly purple on PH high range.

Permalink Reply by David Demner on January 12, 2015 at 5:55pm

How many/size fish and plants? Water temperature? Oxygen levels ok? Water pretty clear? Any possible contamination from the new equipment?

Tilapia are pretty tough so they should recover if your system rebalances.

I haven't used chemical pH stabilizers before but I'm guessing you did your research before adding them.

Permalink Reply by David Langham on January 12, 2015 at 7:33pm

There are about 18 2" fish left. I don't have anything to measure oxygen, but they started nipping for air quite a while before this event and I added an air stone and they acted happy again. The PH Down was from a pet store for aquariums, I assume it's safe. The water is usually pretty clear. I used PVC sheet to line the inside of the new addition. I'll try to attach a pic.

Permalink Reply by David Langham on January 12, 2015 at 7:36pm

Can't seem to attach a pic. There are 2' tomatoes several beans, peppers and a few other things in grow bed, and lots of little lettuce plants in DWT