# Sulphur smell in sand. Normal? Toxic? Can't find straight answer.



## Sikka (Jan 12, 2011)

Hey again... (made the important phrases bold so you don't have to read all my rambling .. !

3 weeks ago I transitioned to a* sand substrate*. Tank's about 6 months old, planted, *10 gallons*, houses 5 corys and a betta. 15% water changes weekly.

*Today I did a 15% water change and was met with a strong sulphur smell when siphoning the sand bed. Like strong enough to infiltrate other rooms in the house*. Immediately hopped on Google and found some articles saying the smell is "normal" when cleaning the sand, others saying it's a very bad sign, indicative of decay and toxicity.

I'm using test strips, so things "look" normal, but I realize these strips are pretty useless for truly accurate readings. 

Lost a cory last week, everyone else seems okay... 

Any advice? I'll be doing a huge water change tomorrow but I'm worried about being able to fend this off in the future as clearly my current routine isn't working... 

Thanks guys...


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## froggle1 (Mar 3, 2011)

I think you should clean your sand. If that doesn't work, leave it be and see if more die.


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## Sikka (Jan 12, 2011)

froggle1 said:


> I think you should clean your sand. If that doesn't work, leave it be and see if more die.


Hm... I probably can't leave it be because the smell is so strong... I actually noticed this smell faintly yesterday, but stirring up the sand really let it loose. It's been about 2 hours and it hasn't subsided.. I've got a 7 gallon water change planned for tomorrow (just waiting for the dechlor to take effect.

By cleaning the sand you mean I should take it out and wash it? :\ I will, but I wonder what happened... the sand is brand new and I washed it thoroughly before adding it...

Any more advice? .. thanks.


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## redchigh (Jan 20, 2010)

Sulfur means part of your substrate is anaerobic. The sulfur is toxic to fish, but a layer of bacteria on the very top surface of the sand should neutralise it before it hits the water column. If you smell sand from the water, then there's simply too much sulfur hydroxide being produced.

I would make your substrate shallower. If it gets too far out of control, you may need to switch out the whole substrate. Plant roots can help eliminate anaerobic sections, but if the soil is too anaerobic it will kill the roots.

I have that problem in one of my soil tanks... It's a pain. Probably need some plants.

Increasing oxygen levels can help, since the aerobic bacteria (that use oxygen) will displace the anaerobic bacteria and narrow their numbers.

BTW, bottled dechlorinators work instantly. High levels of sulfur is more toxic than the low levels of chlorine.


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## Sikka (Jan 12, 2011)

redchigh said:


> Sulfur means part of your substrate is anaerobic. The sulfur is toxic to fish, but a layer of bacteria on the very top surface of the sand should neutralise it before it hits the water column. If you smell sand from the water, then there's simply too much sulfur hydroxide being produced.
> 
> I would make your substrate shallower. If it gets too far out of control, you may need to switch out the whole substrate. Plant roots can help eliminate anaerobic sections, but if the soil is too anaerobic it will kill the roots.
> 
> ...



Great information! Thanks so much!


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## Sikka (Jan 12, 2011)

Just updating to report that the problem seems to be solved. I went ahead and moved forward on the water change, removed a bunch of the substrate as per the advice given here, and the smell was gone almost instantly.

Thanks again, guys.


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