Originally Posted by penny.1919pp
Hello, Thanks for your reply. Its a 40gallon tank and ran for 7 - 8 months with no problems until now. Yes just the media changed in the filter and all double triple checked its correct? Im upset because I love the fish and the tank but now its like a green pond
Well for one that filter is def not big enough for the tank. It's amazing that your tank stayed "clean." While the water may have been clear, your levels of nitrate, nitrite, and ammonia had to be through the roof! That filter is only good for up to 20 gallons and even that's pushing it. Do yourself a huge favor and get an AC
110. Your tank will not get any better with your current filter I can promise you that. Also, by changing ALL of the media your starting a new cycle. Beneficial bacteria grows on the media and when you remove it all at once, your drastically reducing the amount of bacteria that has built up to remove organic waste (ammonia/nitrite). If you are not familiar with what I'm talking about, look up "nitrogen cycle."