tank smell

Question
I have a 55 gal freshwater aquarium with around a dozen medium-large cichlids. I am having a problem with extreme tank odor. Tank was fine for a year with no problems, the odor started six months ago and seems to be getting progressively worse. I have always used a gravel vacuum to take out about 10 gallons of tank water. I have done this more frequently, every 10 days, recently because the odor is getting worse. I've had a UV steriilzer for a few months. I have two 55-gallon pumps/filters (1 AquaClear Power Filter for a 40-70 gallon tank and a large Top Fin filter) on the tank with a large air stone. I clean my filters twice a week and replace as needed. About a month ago I removed all the gravel from the tank and have not put anymore gravel in. I have no live plants in the tank at this time...just fish and water. What else should I be doing to get rid of the tank odor?

Answer
Hi Jacob,
 The main cause of bad odor from a fish tank is either dirty water (which doesn't seem like the case from what you tell me) or just uneaten food in the tank.  Are you feeding your fish too much?  

 As you suspect, a "normal" aquarium does not smell bad at all.
I assume that you checked to see that there were not any dead bodies lying around behind the tank.

-- Ron C.
  rcoleman@cichlidresearch.com
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