Added Powerheads... Fish are dying.

[Will25U]

This is a couple of posts I put on another forum, and am looking for some help, if anyone can. Thanks

This was posted on Thursday, the 19th:
I bought 2 750 gph koralia powerheads, and installed them yesterday. One on each end of the tank blowing towards the middle Of the tank at different angle to voice off the front glass. Everything looked fine before I went to bed. This morning when the lights came on my wife calls me to tell me that our Midas blenny is dead and getting eaten by our CUC. Also she said the maroon clown we have is not looking good either. I had her test water params and the came back As follows:

Nitrates 0
Nitrites 0
Amonnia .25
PH 8.4

We have had the blenny for about 2 weeks now and the clown for about 2 months. Tank has been set up around 7 months now. I didn't point the powerheads towards the sand, so not a lot of sand got kicked up. Could the powerheads have stressed the fish to death? The rest of the fish in the tank seem to be doing fine. I had her turn the powerheads off before she went to school. I will do a 20% wc when I get home, but am at a loss of what really happened. Any ideas from the group? Thanks

Later in the day on the 19th:
Well got home, and no more casualties YET. All fish are breathing extremely fast. Did about a 20% water change and tested the water. Everything reads 0 now. I tested the water with the volt meter and maybe I'm doing something wrong, I don't know but got 52 volts with nothing on in the tank. I doubt that is right but I get the right voltage from the wall 121 volts. Corals are not looking good either.

Saturday the 21st:
So I finally got a chance to completely multimeter everything in the tank. And EVERY thing I plug in adds more voltage to the tank. I unplug Everything and there is 1-2 volts still in there. I plug in a regular table can that is near it, it jumps to 5 volts in the tank. I plug in my practically brand new skimmer, it jumps to 31 volts. I unplug it and plug in return pump I get 20 volts, I plug in the heater I get 50 volts. Everything gives different amount of volts but it seems like everything is adding volts, which it shouldn't. I tried grounding the multimeter to a different plug to see if the ground was bad, but still same volts. Tried plugging just the heater into another socket with an extension cord, same thing.

Another of my fish died last night. The brown dragonnet, and the green chromis is just spinning in circles. Maroon clown and highfin seem fine, along with the CUC. The corals mostly seem fine with the exception of the Xenia which look a little better today. I really am at a loss. Maybe it's my multimeter I don't know.

Any help would be greatly appreciated. Sorry about the length of the post.

[Peter Eichler]

What is your carbonate hardness/alkalinity, and do you supplement to maintain it? Have all fish died at night? What are you testing your PH with?

[Will25U]

Alk is 3 with a SeaChem test kit, and for all other params I use an API Saltwater master test kit.

Blenny died early morning(8am) and the brown dragonnet died late evening(midnight). I have B-Ionic, but have not dosed recently.

[Peter Eichler]

Assuming that your alkalinity is accurate, and you didn't stir up your sandbed, I'd suspect some type of parasite.

You may want to test with your carbonate hardness with API as well, in fact I prefer their test to the Seachem. The troubles you're having are probably just a coincidence in relation to the powerheads.

[Will25U]

So you don't think it has anything to do with the voltage? I believe I also have an API alk test kIt. I'll try it.

[Peter Eichler]

So you don't think it has anything to do with the voltage? I believe I also have an API alk test kIt. I'll try it.

No, I wouldn't worry about the voltage. Your readings are quite normal... Plus, stray voltage being harmful is still the remnanats of some misplaced diagnosis from years ago and some aquarium companies wanting to make some money on a hunk of metal and wire.

[Will25U]

Ok, well could it have been a coral that started putting chemicals in the water when I added the powerheads? I have a bubble tip anemone, frogspawn that could have put off some strong chemicals. I doubt the rest would, but here they are. Pulsing Xenia, a mushroom, and a couple of palys.

[Peter Eichler]

Ok, well could it have been a coral that started putting chemicals in the water when I added the powerheads? I have a bubble tip anemone, frogspawn that could have put off some strong chemicals. I doubt the rest would, but here they are. Pulsing Xenia, a mushroom, and a couple of palys.

Quite doubtful. Chemical warfare in corals and anemones is usually with the design of limiting growth in other corals. I've never seen any evidence that they will harm fish in any way.

[Anemonebuff]

Did you wash the PH's prior to adding them? Anyone spray any chemicals near the tank?
Sounds like whatever it is it is affecting the fish's neurological system. High stray voltage my cause a similar effect.

[Cloudburst2000]

Well, I would personally suspect the blenny that was added to the tank. You said it was only in there two weeks, right? I'm taking it that you did not quarantine the fish? I would suspect that the fish was ill when you added it to the tank, and whatever the illness was has infected your remaining fish. I would set up a hospital tank and remove all remaining fish to the hospital tank for treatment. I would also suggest that you quarantine any fish in the future.

[CoralReeferGal]

Could be too much flow (which will stress out the fish), since you had no issues until immediately after putting the power heads in. What did you have previously in comparison to the flow now? What do you have for means of gas/oxygen exchange? There should be returns or power heads pointing at the top for gas/oxygen exchange. You may have changed your oxygen circulation the way you set these ones up. You can also try adding an airstone, which will help the fish breathe better and will slightly help maintain the ph after the lights go off.

[Will25U]

I have a 75 galling with a 20 gallon sump. I don't know the gPh of the return but I had one of the Ph up a little to get surface agitation. Had my two return nozzles pointed behind some of the rockwork in the back. I turned the Ph's back on today and everything seems fine so far.