# how to avoid that 'fish tank' smell



## Jules (May 20, 2012)

I've had a 50 gal in the living room for years - I feed a LOT (serious over feeder - but it all makes yummy nitrates for the plants) and only do a small water change every couple of months, but I've never noticed any smell at all from the tank. 

If I literally stick my head inside the canopy and sniff the water there is a slight earthy smell - but you'd have to really have your head right over the tank to smell it. 

The only time where there is a noticeable smell is when I have the water level down very low to catch fish or something, exposing a lot of the bog wood and stuff. There's a pretty strong swampy-earthy smell then (from the biofilm). It disappears as soon as everything is under water again.

Is it a smell like damp earth you're smelling? Or something more unpleasant?


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## Phish (Apr 29, 2009)

more water changes. 40-50% once a week. maybe 2, 20% changes a week to help with the stank.


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## jbrady33 (Jun 7, 2012)

earthy and green is exactly how I would describe it.


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## mistergreen (Dec 9, 2006)

jbrady33 said:


> earthy and green is exactly how I would describe it.


that's not THE fish tank smell.


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## Jules (May 20, 2012)

jbrady33 said:


> earthy and green is exactly how I would describe it.


Sounds like a normal smell then - I wonder why it's so noticeable. 

Do you have an open top tank? With an open top and strong air circulation (is there AC?) perhaps the tank smell is getting picked up and wafted around the room?

This is just a total guess on my part though since I've never had this problem with my open top quarantine tank either - although I don't have AC or forced air, and that might make the difference.


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## steven p (Jun 22, 2012)

Try to up the circulation or aerate for a few days and see it it helps, maybe your biofilter needs a little more oxygen.

Are your fish growing and pushing the bioload of the tank?


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## ramen lover (Jun 22, 2012)

When I had a glass canopy lid my tank smelled a little when I opened it. Now I have custom made window screen mesh and my tank doesn't smell at all. Plus my water circulation is very good


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## hydrophyte (Mar 1, 2009)

I have observed bad odors from fish tanks when I have used foods containing garlic.


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## AquariumNoob (Aug 18, 2010)

Jules said:


> I've had a 50 gal in the living room for years - I feed a LOT (serious over feeder - but it all makes yummy nitrates for the plants) and only do a small water change every couple of months, but I've never noticed any smell at all from the tank.
> 
> If I literally stick my head inside the canopy and sniff the water there is a slight earthy smell - but you'd have to really have your head right over the tank to smell it.
> QUOTE]
> ...


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## WallaceGrover (Jan 15, 2011)

I used to have that smell too, it's what you would smell walking into a LFS. It's not really bad you can just immediatly associate it with a fish tank. I don't have it anymore, for reasons I don't know....


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## Bubba Shrimp (May 7, 2012)

changing your carbon is very important, once it reaches max absortion toxins get released back into the tank


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## HD Blazingwolf (May 12, 2011)

if it smells earthy. it should it means ur bacteria is working to break down stuff in ur tank and turn it basically into dirt. IE the earth smell

if it is overpoweringly strong. there is a lot of dirt making going on so try feeding a little less and see if that helps

OR u can try changing water more frequently as that will remove the "pre-dirt" LOL or the some of the organic load

the good news here is it is a healthy smell.. means plants are growing and ur system is doing what it is supposed to be doing... having a clean cannister helps. i find its easy to let cannisters go a long time between cleanings especially so with floss cause it keeps doing its just but it does turn into a nitrate factory taht way and can exacerbate any smell


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## mcarroll (Apr 14, 2008)

This is the time of year for a lot of us when the weather is "in between" and the HVAC system doesn't run very often.

HVAC cools or heats the air (coincidentally drying it a little in the process), but also replaces stale air in all the rooms with fresh air from the cold-air return system. None of that has been going on, or has been at a reduced frequency and the every-so-slight smell your system(s) generates is allowed to build up more than normal.

Running a fan and/or dehumidifier should be all it takes to get rid of, if you want. It will likely clear on its own once we're into the next season and your HVAC is back in full swing.

-Matt

P.S. As far as the source of the odors it's almost surely the canister. It may be time to replace your carbon even if the rest of the canister appears to be "clean"...which it may not be if you're correct in your over-feeding assessment. I would take a look to confirm if you haven't already. Odors indicate most likely that the carbon is spent, at the very least.


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## jbrady33 (Jun 7, 2012)

I do plan on a full canister cleaning, replacing purigen and carbon this weekend. Smell hasn't come back since doing that water change, I think a combination of some melting leaves and switching to Omega-One color food (first ingredient is Salmon).

I usually guess at the state of the canister by the look of the pre-filter in the tank, it has done a great job of keeping bigger stuff out of the canister. Not really that noticeable behind the plants either, the return is more obvious in the pictures.


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## TexasCichlid (Jul 12, 2011)

Bubba Shrimp said:


> changing your carbon is very important, once it reaches max absortion toxins get released back into the tank


I was told this is a myth.


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## Diana (Jan 14, 2010)

> once it reaches max absortion toxins get released back into the tank


This is false. Activated Carbon holds onto pretty much everything so well that there is no way to rejuvenate it with methods available in the home. 

It is very good at removing odors, so perhaps some cleaning, followed by a couple of changes of AC (perhaps weekly or more often)

Other smells in an aquarium:
Ammonia or 'cat pee': really is ammonia. 
A sort of earthy smell, but not so good earthy smell. Hard to describe, but Cyanobacteria, aka Blue Green Algae. Some species smell worse than others. It does not take much. I would do a thorough cleaning in all the niches around the tank like the corners of the rim, the joint where the parts of the lid come together and so on. BGA comes off pretty easily, an old toothbrush and a good rinse will do it. You can also use hydrogen peroxide where it won't run into the tank. (for example, clean the lid in a sink or the bathtub) 
Dead fish smell: A dead fish. 
Other (worse) dead smell: Dead Apple Snail.


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## roadmaster (Nov 5, 2009)

Bubba Shrimp said:


> changing your carbon is very important, once it reaches max absortion toxins get released back into the tank


 
No,this does not happen.
In order for carbon to release what it has Absorbed,,it would need' to be subjected to temperatures not achieved in the aquariums.(100's of degree's F).
Or you could boil the carbon.


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## Gplus (Apr 2, 2012)

Do a 40% to 50% weekly. That'll keep more fresh water rotating and hopefully get rid of that smell. I do a 40% on my 55 weekly and I have no smell.


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