So my tank was finally at the end of it's in fish cycle, so I decided to add 10 lbs of sand substrate to benefit my cory's because I know even the fine gravel might hurt there little tummies. <3 I washed the sand thoroughly, in conditioned water, turned my filters off, added the sand, waited about 5 minutes for it to settle and netted as much floating particles as I could, and turned my filters back on. Well low and behold I woke up the other morning and both my filters had clogged and weren't pumping water. Cleaned them, turned them back on. Tested my level's, everything was through the roof. Nitrate is around 20 ppm, ammonia between .50 - 1.00. Within three hours, I lost both my panda cory's, probably to poisoning since they turned completely white and died. I lost my black female platy as well. I was able to net a few fish and put them in my other cycled tanks temporarily, but I don't wanna overstock them and cause those cycles to go out of wack so now I have a potential fish graveyard on my hands. 40g still has... 2 albino corys, 2 emerald green corys, 2 adolfoi corys, 4 agassiz, 1 sunburst platy, and 2 or 3 cherry barbs still left in it. Can anybody give me any advice on how to save these guys?