Long story short, I'm using a 10g QT to house some fish intended to cycle my 75g tank. Daily PWC
's have kept the 3 important toxins down to a minimal.
This afternoon I noticed an awful sulfer-ish smell coming from the QT and that 4 of the 5 damsels were dead.
I move the survivor to a temporary bucket (kept on hand for water changes) with the same tank water, mixed up 10g of new salt water, let it settling out, and then drip-acclimated the damsel to the freshly made water.
I rinsed the tank out thoroughly, scrubbed down with my cleaning brush, rinsed in some of the new water, rinsed again, and filled it up.
There are 3 decorations in the tank, the fake rock-like things you get at the LFS
. They all smelled awful when I was cleaning the tank.
I also soaked and scrubbed down the 3 decorations really well in near-boiling water, then let them dry (and cool) before going back in the tank. Rinsed them off with more pre-mixed water first.
The damsel is fine, snapped back from a coma-like state pretty quickly, but the sulfer-ish smell is back. Really bad. I can smell it from 4 or 5 feet away.
My 75g tank (which is at its peak nitrite level right now) never smelled like this.
Is this a filtering issue? I have a small 10g air-powered filter, 2 stage, with sponge/foam at the bottom and charcoal above. There's also an air stone, if for anything, is in there for better circulation.
I'm worried I'm going to wake up to find my last little blue guy gone...