Backyard Aquaponics
A place to discuss aquaponics

I'm in Perth and I've been using tap water for years in numerous systems without any problems, always straight out of the tap, never with conditioners... Strange......

Hummm... what have you been putting the tap water into Timmy.... another container of some sort. Or just using a hose?

i think there probably your answer. i suspect some of those chemical might unstable the aquaponic balance. think of an ap system as a huge organic web of life. the more organism's exposed to chemical's the less stable it becomes. sure some of the organisms may survive and keep ammonia levels down, however the complex organic process is out of whack. this can probably cause havoc to the immune system of the fish. i think you are far better off having a separate tank with a pump to dechlorinate. this will also keep the do levels high for when adding to the system.

imo you should stay well clear of any chemicals. after all this is one of the benefits of ap. no need to use chem's.

ironic that in an effort to keep my fish alive i might have been killing the poor buggers.
i'll just let a 20L tub stand for 24 hours before adding it next time.

well no more water added and no more deaths. i'm going to add 20L of water tommrow and see what happens - it's been aged out in the open

here, there is hope that it solves your problem

well, i added 5 more fish to try get some more nitrates going (tomatoes are feeling the pinch, strawberries too greedy) and i also added 40L of aged water and none of the fish are showing any signs of stress, and it's 24hrs later. usually one would have died by now.
i'd say case closed.