What is the temperature? And do you have a lot of aeration when you have your pump running? what tank size and number/size of fish?
It could be that the oxygen level is already a bit low when the pumps are running so when you cut off the pump this low level of oxygen is depleated fast. I can't think of anything else. Ph is a little low if it was day time with light and aeration so that could be it.
Are they breathing fast?
__________________
_________________________
More fish die from human stupidity than any other disease...
|