I have a 10 gallon and I think it has aerobic bacteria problems because the water smells like rotten eggs; it's done this many times, and I'm sick of it. I think I should clean out the tank totally, and only put in a small layer of gravel. Since I have fish in there, should I put back maybe 10% of the tanks current water? If there is anything else I should do, don't hesitate to add. Thanks.