I need to know what to do next: OK, all my fish have died over the past 4 days... angel fish, 2 gouramis, 2 pleccos, 1 catfish. Sumo loach is only one remaining. Here are stats:
fresh water aquarium
Bio Wheel filter system
About 6 days ago I washed the bio wheel, cause it wasn't turning, and this is what the local aquarium store said to do. But I washed it in chlorinated water, not thinking it would do anything. I also replace one of the 2 carbon fiber filters.
About 3 days later fish started acting sick... angel fish first, then others quickly died, with gouramis the last ones last night. Sumo loach is left. Gouramis had white spots/ich. Nitrate was 40-80 range. I did a 50% water change 2 days ago, and nitrate was still high last night. Put de-nitrate rocks in the filter box last night.
What should my next steps be? Should I go ahead and put ich treatment in the water as if there were sick fish? Do water changes every day (how much?), and just wait for the nitrate to go down. I can't start from 0 again, as I still have the loach.
Many thanks for any advice you can give!