Els Engel:
Ok, now I've heard from at least three different people and some books: 'if something is out of balance, stop feeding'. It's very hard for us to imagine but fish can apparently stay happy for weeks without food. Is this an idea?
>Lidewij Servatius:
This is an idea, but i think it is good to keep feeding just a pinch every day. That will keep the bacteria happy. If things get better you can gradually increase the amount of food. If you stop feeding for a week it takes a lot of time to get back to the normal amount, or things will soon be out of balance again.
Another question: what's the role of oxygen in this story? If CO2 is high, is oxygen low? Or doesn't it have a relation? Because you said CO2 makes it difficult for fish to take up oxygen, didn't you?
>Lidewij Servatius: Like Oxygen CO2 binds to hemaglobine. Normally the CO2 is easily given off to the water when blood flows through the gills. O2 will take the place of the CO2 and get into the bloodstreem. If CO2 in the water is elevated, the CO2 on the hemaglobine is not so easily given off to the water and it tends to stay on the hemaglobine and go back into the bloodstream instead of O2. CO2 has a lowering effect on the pH of the blood of the fish (like it has on the water) beside the shortage in oxygen, this also causes stress to the fish. Signs of CO2 poisoning in fish are hyperventilation and red gills.
About the same story accounts for nitrite. Nitrate sticks to hemaglobine tighter than oxygen does.
And another one: if CO2 would not be the cause of this situation, does low pH and high KH still automatically mean CO2 is high in the water?
>Lidewij Servatius:
Yes like you can see in the table High KH and low Ph will end up in the red zone. The red zone is where fish can get into trouble. In natural situations you would be in the yellow zone.
It is good that we will build a new system tomorrow. Less fish in a system also means less CO2 production.
Do the lights go out in the tents at night? or do they stay on permanently?