Im posting this for a friend that isn't on here, any help or insight would be greatly appreciated.
Set up his tank about 3 months ago 180 gal with sump, fuge, & skimmer 150 lbs live rock. After curing rock he used one of those bacterial kick start solutions, waited a month or so, water tested out good and put in a few chromis, long story short he lost quite a few fish over month time period, when I looked at onw of the fish after it died, it had uronema, and explained the loss of his chromis's as they are very susceptible to uronema.
OK long story short. The other day he went downstairs and he lost 2 tangs, and a clown over night and a fire shrimp went mia. They did not have any markings or signs of uronema or attack by something in the tank. He said they were fine the night before then in the morning the water was cloudy and the fish were dead. I told him to test his ammonia asap and it came back 0.
My question is, is it possible that he is going through a cycle and ammonia is whats killing the fish but still giving us a 0 reading on 2 different test kits ? I saw somewhere that cloudy water can be a bacterial bloom that was brought on by a spike in ammonia but the bloom is consuming the ammonia and causing a false reading. Does that make sense to anyone on here? Can anyone think of a reason for a mass die off like this ?
I have personally tested his water:
alkalinity 7.8dkh hanna
Phos 0ppm hanna
calcium 380ppm hanna
Mag 1200ppm red sea
nitrite 0 api
nitrate 0 api
amonia 0 api
Plenty of turnover through sump, he has 2 return pumps rated at 2,000 gph each (running at 30-40%) and he has 2 MP40's
I thought of low O2, the tank is in the basement and its built into the wall with the entire
back side of the tank and sump in the boiler room. But it has a skimmer going and macro in the fuge, I could be wrong but thought that even if theres low O2 in basement environment effect wouldnt be enough to suffocate fish being that they hang out in basement.
Is there anything internally in the tank that can consume all of the available O2?
How would we test the O2 level ? I have heard to test the ph in tank water, in place then take a sample outside agitate it and then test ph again, assumption is that O2 effects ph so if ph goes up then O2 must have gone, but Id assume that this would happen regardless of if O2 was "low".