It has to be a bad sign when I'm the only one posting to the forum.
Came home from work today to find the airline blown going to my pool. Not sure when it happened but nearly all my fish were dead. I pulled about 35 9" Tilapia from the bottom that were very recently deceased (clear eyes, still malleable bodies; i'm guessing maybe a couple hours at most. I even found one the had a single gill still moving - held it directly in the reestablished air flow and after five minutes it swam away.
The dead were fresh enough that we are cleaning them; some for dinner and some for the freezer. Not huge but I've had smaller pan fish.
So my lesson from this - Run a redundant air pump in case a line blows or something. My setup was around 40 fish in a 600 gallon pool with a 70lpm air pump into a 9" micro-bubble disc. They suffocated in less than 12 hours, so a second pump would be a smart safeguard.
The other thing that caught me off guard was literally hundreds of fry, all about a quarter inch long. No idea if they are Tilapia but no idea what else they could be in a closed system. I did not have a breeding pair, but if the fry were talipia, then somebody was a cross dresser.
Here is a mishap of my own that I am currently struggling with. As more than one thing went wrong at once, I am not 100% on cause and effect here. I added tilapia to my system at the end of August. The system was cycled and I was confident that it would be stable. Still, I kept daily vigil over Ammonia, Nitrite and Nitrate, and occasionally DO. For two weeks, all was stable: Ammonia never over 2.84 mg/l, Nitrite never over 0.24 mg/l and nitrates hovering between 9 - 10 mg/l. Then my daughter, aged six, decided to help in the drought by tipping a small bucket of washing machine water into the grow bed. I noticed the fish were not very happy, and the ones showing the most stress got a salt bath. I got the settings on a new fish feeder wrong, and it was dumping food into the system at night too, but as the fish could deal with it, I never noted a lot of residue. I was still wondering why they were not so keen on food by day when on a hunch (looking at fish behaviour and water cloudyness), I decided to look at more water quality tests. Oi!! Nitrites at 7 mg/l.
I am close to lethal limit for these guys, but am keeping a close eye. cycles seem to be stabilizing, but I will do a water change if the Nitrites are not heading down by the end of today. Anybody here have any idea if the washing machine water, about half a gallon, could have wiped out my bacteria completely?