What to do? Opinions needed.

[Delphinus]

I don't know what to suggest. Before the move I was battling dinos for the second time, and getting nowhere with it. Tried the lights-off thing, no difference, all the other remedies you tried, same result.

After the move it just went away. I have no idea what did it. The fact the halides were off for almost a week ... the major disturbance of the rock and sand bed ... who know. It's really quite strange that the tank that was having problems before the move, got cured by the move (despite the sand bed disturbance et. al.), and the tank that was fine before the move, has had livestock losses, and problems still since. Long way of saying "I have no clue what's going on here."

The only thing that I didn't see in your list of options, that I was about to try, had the problem not gone away on its own, was a UV sterilizer. I still don't know if that would have been a "good" option but I was ready to try anything to get rid of that crap.

Hang in there. I know it's disheartening. At times I was ready to admit defeat and do a tank tear-down ... so I know how frustrating it can be.

Good luck.