I have a 55 Gal tank. It has 1 1/2 inches of gravel, bubble wall, skelton air bubbler, 3 plastic plants. golf ball, basketball orniment and a fake wood cave with fake plants on it in the tank. I also have 2 whisper ex70 filers in the tank. I have only had my tank up for about a month now. I have cleaned the gravel and did a 25% water change on it. We have 10 fish and 1 crab in the tank. It is making my house smell nasty, my husband says he doesn't smell it, but I can when I come home from being out of the house for even an hour. What can I do to make the smell go away???