Peculiar Aquarium Odor

Question
Hello - Thank you, first, for making your expertise and time available to the
public. I have had a 10-gallon aquarium for more than a year now, with 6
healthy and compatible fishmates (fancy guppy, cory, blood-finned tetra,
white cloud, balloon-bellied molly, flame gourami). The only live plant is a
similarly healthy lucky bamboo. I perform weekly filter changes and 15%
water changes with religious zeal. The tank is an Eclipse with a top-load
filtration system. For the past 10 days or so, I have noticed a peculiar odor
which seems to originate in the filtration system itself - not in the water. It is
a sweet - (borderline sickening-sweet) - smell, almost like something sweet
baking - nearly burning - in an oven. No other changes of any kind to report,
and it is business as usual with all the fish. Last week's filter and water
change did nothing to correct the odor, and the next filter/water change is
scheduled for tomorrow. The only additions I make to the replacement water
are a de-chlorinator (applied 24 hours in advance) and a teaspoon of sea salt.
Any suggestions you might make would be greatly appreciated, and I thank
you again for your generosity.              Best Regards, Kirk

Answer
Karen
I would check the eclipse well as there may be food build up trapped somewhere.
I would also stir up the gravel to see what the build up is there.
Fresh carbon will eliminate the smell but we want to find out the cause so that it wont become a reoccuring problem.
Let me know how you make out.