RIP Bristles...

Whatever was wrong with the Bristlenose Catfish he's not suffering any more. After posting last night about him, I altered the pump and then 3 hours later found him dead underneath it. No real further clues as to what was wrong - an air embolism in his stomach seems to have killed him.

But also this morning I noticed the Guppies at the top of the tank, a cory swimming diagonally and the Danios didn't react to being fed. Instantly the air pump was switched back on, the pump raised so that it disturbed the water surface more and the temperature knocked back down to 24 Celsius.

We went to the fish shop to replace the Bristlenose and took a water sample, which she tested and said the Nitrites were up! Got home and checked for myself (to make sure I'm reading the tests properly...) and now I know I'm reading them correctly. The Nitrites aren't worryingly high, but it's a puzzle as to why they are reading. I'm guessing that maybe reducing the air supply has also affected the nitrifying bacteria, and they have not had enough oxygen to process the waste. I'm guessing, from O level Chemistry quite a few years ago, that the equation goes something like...

NH4 + 2O2 = NO2 + 2H20 (ph < 7 here, so it's ammonium - NH4, instead of ammonia, NH3)

2NO2 + 02 = 2NO3

So every 2 molecules of ammonium need 3 molecules of oxygen to be converted to nitrate... Probably wrong, I failed O Level Chemistry first time around.