I have started up a new tank and have cycled with fish. Everything is good from what I can see. Ph ammonia levels are normal and fish seem to be just fine. I did have a small heater that I believed wasn't enough to heat the tank. I was wrong and the heat shot up. Not to a critical stage but on the cusp about 80 degrees. I did lower it back down but I am curious to why this smell is coming from the tank. Its a 55 gallon tank with 2 30 gallon filters. I beleive that as I lowered teh temp the smell went down, either that or opening the windows did alot of good.