# Sewage smell...



## AlexH (19 Nov 2016)

Hi guys

Just done a water change and i used tap water. i kick started the filter without first adding the water treatment. stupid - i know..

I quickly turned the filter off after realising and added the water treatment.

Filter has been running for 10 mins and theres an odd smell comming from it. like a blocked sewer.

I have no idea whats going on? any clues?

Thanks


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## sciencefiction (19 Nov 2016)

I've ran my filters without treating the water numerous times. I doubt it that's what caused the smell. If anything, the chlorine would have "killed" the smell. How do you know the smell is from the filter and not the tank water itself? My guess is the tank needs a very large water change, filter clean and check around anaerobic places where the smell could be coming from...The water flow probably uncovered the source somehow...


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## AlexH (19 Nov 2016)

Hi

Ive just done a 90% water change and did a full filter clean a week ago. 

The smell has since gone though


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## dw1305 (19 Nov 2016)

Hi all, 





AlexH said:


> Filter has been running for 10 mins and theres an odd smell comming from it. like a blocked sewer.....Ive just done a 90% water change and did a full filter clean a week ago.


 Is there floss, or fine sponge, in the filter? 
and
was there a lot of "gunge" in the filter last week when you cleaned it?

cheers Darrel


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## AlexH (19 Nov 2016)

dw1305 said:


> Hi all,  Is there floss, or fine sponge, in the filter?
> and
> was there a lot of "gunge" in the filter last week when you cleaned it?
> 
> cheers Darrel



Yes  and yes


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## dw1305 (19 Nov 2016)

Hi all, 





AlexH said:


> Yes  and yes


OK. 

Two options then,  in the "floss" scenario the water in your filter has become de-oxygenated within the filter. This is much more common than people realize, particularly if they use their filter as a syphon aiming to have both mechanical and biological filtration occurring in the filter. 

The main problem is that a finite volume of oxygen enters the enclosed filter body, and it can't be replenished  in the water inside the filter. 

If you have floss, or fine-sponge, this becomes much more likely because the retention time of the water in the filter is longer, and often you get tracking where the water takes the path of least resistance in the filter and some water remains in the filter for considerable time periods  and this de-oxygenated, ammonia rich water could be the source of the smell. 

For biological filtration to function properly you have to ensure that the water in the filter remains oxygenated, again a lot of people don't realize how important this is, particularly if you have an un-planted tank.  I don't have any fine material in the filter body and I have any mechanical filtration carried out by a pre-filter on the intake.

In the "over-clean" second scenario you've removed a lot of the nitrifying filter bacteria and the remaining micro-organisms are unable to cope with the ammonia load, again leading to the ammonia sewage smell.

cheers Darrel


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## Crusader58 (20 Nov 2016)

the water treatment you used wasn't seachem prime was it?...as this can give off a rather foul smell.
just my tuppence worth.


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## AlexH (20 Nov 2016)

It was interpret bioactive tap safe plus


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