I finally rigged up the plumbing completely and the system now cycles at about 420 gallons per hour. With the tank carrying 275 gallons, both the sump and the biofilter holding 50 gallons each, and both growbeds holding 15 gallons each, I'm just above my target of 405 gallons per hour (which would cycle the tank once each hour). I have however, run into a problem. Two days ago, I had one green sunfish die. Yesterday, about 15 fish died. Today, I found 5 fish dead. I ran tests last night after it became apparent there was a problem and the results are as follows: Ammonia- 1.5 ppm Nitrite- .12 ppm Nitrate- 2.5 ppm pH- 6.2 I don't see anything totally amiss with these readings, so the only thing I can think of that could've gone wrong is that two nights ago the air temperature dropped about 25 degrees from the daytime temperature. With the rapid turnover rate the system was experiencing, the water cooled too quickly and the fish became stressed and died. I'm curious if you guys have any other theories as to why so many fish have died?
