odor

Question
Hi Karen and thanks in advance,  My problem is an odor has developed in my two main tanks a 120gal and a 55gal, I keep mostly Malawi cichlids. The tanks in question are very mature over 5 years old. I have never had an odor in my water, I consider myself almost freakish about my weekly water changes, I ONLY use conditioner, cichlid salt and Malawi buffer in my water. I pre mix my new water 65-70 gal at a time then pump it into each tank. The 120 is being filtered at a rate of 1200 gal per hour with four back (power) filters, the 55 has two back filters filtering at a rate of 550 gal per hour. I've used the same products for the duration of the tanks lives, however about 5 or 6 months ago this very harsh odor developed and even when I completely break down all filters on the same day and completely clean them out ( except for the bio media which I rinse thoroughly in existing tank water as to not kill my good bacteria)by one or two days later the odor is right back again. My temp in both tanks is 82f, pH=8.2, very low nitrates, and no nitrites, I rarely lose fish and have some over six years old in each tank, I never overfeed, feeding the same quality veggie flake since I started, when I feed, once a day, the food is completely gone in less then 2 minutes. Here is the only thing I can think of and I hesitate because everyone I know says it could not be this. I started feeding New Life Spectrum brand Cichlid pellets about a year ago, it is an excellent food source, my fish never have looked so good since starting this food. I feed it along with the flake. Do you have any info on what could be the cause of this odor? Do you have any knowledge of New Life Spectrum pellets? Do you know if back filters in general have odor issues or if a canister would be a solution? That doesn't make sense because I have had the back filters from the beginning and only recently have odor. My tanks are very clean, my fish are very healthy (and beautiful) but this odor is causing me to pull my hair out, its letting the air out of my fishkeeping sails and I never thought I would ever say that. Please help if you can  John

Answer
Hi John,
Odor in the aquarium usually means there is an organic or chemical causing the odor. Organic being of course waste and debris in the aquarium. This may be silly to ask but have you made sure to try checking behind and underneath decorations and rocks for buildup of waste? You mention its a very harsh odor -- does it smell like ammonia? Or is it a 'fishy' smell? Or perhaps it smells like swamp?  A healthy aquarium will naturally have a "earthy" odor very similar to the scent of freshly dug up dirt. It shouldn't be overpowering however....that might mean something could be off balance.

That's good that you tested for nitrites and nitrates. How is the ammonia level? just in case you might want to check that.

I think this will definitely take some investigation work. How is pure tap water itself? does it have a strong odor? Perhaps its the water conditioner you are using? Some do have very strong odors. But these should subside after a bit.

Have you tried using your nose to search out if there is any particular concentrated source of the smell?

I don't really think the new food would be the cause of the issue here. But its important to not leave details out like that - that can sometimes help pinpoint a problem.

Sometimes you can have a chemical reaction between chemicals you use but you only use water conditioner. The salts shouldn't be responsible and I don't think the buffer would be either.

The filters you have generally do not have any issue with odor when maintained properly and the fact that you have checked and cleaned them out obviously means that can't be the reason here.

Consider some of those things I've mentioned and you should be able to make some progress one way or another with figuring out what might be wrong.

The good thing is that your fish are doing well and are healthy! ;-)

Hope this helps!
Karen~