wouldn't it stress the fish if you do water changes 2 times a day everyday for a week? the bigger filter was a good idea. IMO take all the substrate out to do a control test of the water to see the lowest posabble factor, and try to find the problem.gonnelro;1773433; said:I wouldnt tear the tank down either - you would just stress the fish, and theres a little bit of BB living in your substrate, and removing it now would be a bad idea. Id just keep up with water changes to keep the levels low enough to keep the fish alive, and hope the cycle kicks in soon. Good luck.