Oops... CO2 Poisoning?
Well I am still tweaking my pressurized CO2 system to try to figure out the proper amount of CO2 to add. I just got a drop checker. The other day, I was gradually turning up CO2 over the course of the afternoon, waiting to see signs of stress from the fish. When I noticed all of my rasboras gathered at the surface, I immediately turned the CO2 off for 10 or 15 minutes until the fish began showing normal behavior again, then started over gradually increasing CO2, being careful not to turn it up too much at once. Well I thought I had escaped any fatalities, but later that afternoon and the next day, I found all 4 of my amano shrimp dead even though they had been doing great just the day before. Ammonia 0, Nitrite 0, Nitrate 20-30, pH 6.4, Temp 76F, GH 3.3dH, KH 1.7dH and conditions have been stable (I've been measuring daily over the past week to get an idea of any fluctuations that may be occurring) and all fish and shrimp thriving up until this event. The only reason I can think of that caused the shrimp to die suddenly is CO2 poisoning. I wouldn't have thought the shrimp would die before the fish, but I don't know anything about shrimp breathing mechanism, so I am not sure. Does it sound like CO2 poisoning?