At what point would alkalinity kill fish?

[jburton0213]

At what point would alkalinity kill fish?

Just got back into the hobby a couple months ago. Got a fish with ich and then moved all fish to a qt for hyposalinity. Then I came across a copper banded butterfly fish, which is my favorite fish and had to have it. Put him in a seperate qt away from other fish and it actually started eating brine shrimp. Moved it to qt and everything was going great. CBB was eating really well. I was so happy considering the the CBBs reputation.

I've been using dkh superbuffer to control ph in the qt. Did a 50% WC last night and had to add buffer to it to bring up the ph to match the qt tank. After water change everybody was good. Got up this morning and checked on them before I went to work. Everything was good. Texted my wife at about lunch and asked her to feed the fish like I usually do. She then calls me and tells me that every one of my fish are dead. A yellow tang, the CBB and 2 crowns. The only thing I can think that it could be is the dkh buffer I'd been adding to the tank. I had the wife check the params, ph was 8 and salinity was 1.009. I'll stop on the way home to get a alkalinity test to know for sure.

 

[jburton0213]

Wasn't alkalinity. Dkh was 7.

 

[Alex114]

Dkh is just a measurement of alkalinity. They’re the same thing. And what are the ammonia, nitrite, and nitrate levels?

 

[jburton0213]

Ammonia on the salifert tester read below .25 ppm (safe) when my wife checked it when she found them and also when I got home. I tested it using the api tester and a sample of water that I had her take when she found them. It read .25ppm. No idea how long they were actually dead in the water when she found them at 1pm. They were fine at 7am. Nitrates were about 10 to 20 ppm. They were higher during the weekend as that's the reason for such a large water change. Cant find my nitrite test atm. Temp was 80 when both of us checked at 1 and 6pm. How prevalent is dissolved o2 an issue?

 

[mcgyvr]

Did you have any water movement/powerhead/bubbler/mechanical filter, etc... in the qt tank?

 

[alton]

If you are having to buffer the water with no corals present, normally that means you are not getting enough oxygen into the tank

 

[jburton0213]

It was under hyposalinity treatment. I read that low ph becomes an issue when you're doing this. Is that not correct?

I have a canister filter on the qt. Theres some surface agitation. I turned the pump on on the wc barrel a few hours before to warm the water up. I'm not sure if this was enough.

 

[wilmaluna]

I rarely measure alkalinity (or anything else except temp and salinity), and it may vary with season since my limewater delivery is dependent on evaporation, but usually it is in the 7-9 dKH range.

 

[Sk8r]

If you weren't running a pump it was likely lack of oxygen. A canister filter just can't oxygenate the way an open sump plus skimmer can, and if there was too little water volume for the fish number and too few air bubbles injected, that would be my instant suspect. Just as a note, best to forget ph and track alkalinity. Ph is up and down a lot in a marine tank: it can cause trouble in chasing it. Alk is much more stable.

 

[wrott]

If you fed too much, NH3 and nitrite, NO2, would be the killer.
Fish would show signs of distress, lethargy, dark color, clinched fins.
30% WC 30 mins after feeding is a good idea, sucking up uneaten food and waste.
I'm very sorry for the loss.