# Anoxic Substrate!?!



## mistergreen (Dec 9, 2006)

It could be a problem. Poke the affected area with a stick everyday. It should clear up.


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## jhunt (May 7, 2010)

If it's letting out H2S then it is anaerobic, not anoxic.


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## Mxx (Dec 29, 2010)

Could be a problem how exactly? I'd read through this page, but it wasn't altogether conclusive for me. http://www.skepticalaquarist.com/docs/nutrient/sulfint.shtml


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## Mxx (Dec 29, 2010)

jhunt said:


> If it's letting out H2S then it is anaerobic, not anoxic.


Is it? I thought anaerobic would have been okay, that would I think mean that bacteria in the substrate were reducing nitrates to harmless nitrogen gas. But the gas does have a slightly sulfurous smell to it.


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## mistergreen (Dec 9, 2006)

Anoxic & anaerobic means the same thing, low oxygen, therefore causing certain anaerobic bacteria to thrive. They produce the sulfur smell (H2S). H2S can be toxic to fish and plants.

Like mentioned, just poke (multiple pokes) it daily to release the gas and introduce O2 into that area.

*Aerobic* bacteria converts harmful chemicals like Ammonium and Nitrite to harmless Nitrate.


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## jhunt (May 7, 2010)

Anaerobic and anoxic are not the same things. Anaerobic means no free dissolved oxygen. Anaerobic environments are also called septic. They promote the growth of sulfide fixing bacteria which produce hydrogen sulfide and methane gasses. Anoxic environments are environments when the free dissolved oxygen is between 0.01 and 0.5 PPM. Certain filamentous bacteria and facultative bacteria thrive in anoxic conditions. In anoxic environments, denitrifying bacteria will grow which will convert nitrate into dinotrogen gas.

Also, nitrate is not harmless, it is just less harmful than ammonia and nitrite.


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