# Sulfur smell in substrate - help?



## OVT (Nov 29, 2011)

The smell of rotten eggs - something is rotting in your substrate, most likely some organic matter.

You do not want to stir the substrate as sulfur is highly toxic to fish.

Instead, use a long straw, small diameter hose, etc to 'poke' your substrate, keeping one end of the hose above the surface. Most of the gas will escape into the air, not into your tank.

v3


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## Aquatic-Prodigy (Jan 21, 2014)

Its just decompossing matter in your substrate dont worry about it wont hurt the fish i would vaccum the substrate and get any excess matter out of it


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## mattjm20 (Nov 2, 2013)

Ok, good call. I realized that would not make the fish happy and was thinking of poking the holes while holding my siphon above it. I'll just buy a thin piece of pvc or some sort of tubing and try out your idea and then do a W/C after that. There is nothing there to rot. The tank is less than two months old so the root systems that do exist are not very large. It's just 1 inch of potting soil under the sand. I was *VERY* careful not to use more than one inch of soil to avoid the exact problem that I'm having right now... Again, my theory is too much sand but I'm not sure, I've never done this before.

Btw - what is interesting is that certain fish do not seem to care at all. My angels, apisto, and bolivians, for example are completely unphased. The boesemani's and black neon tetras do not seem to deal as well.


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## OVT (Nov 29, 2011)

The hose from your siphon should do just fine. That's what I used on one of my tanks (1/2" I'D). I did not want to use a larger diameter in the fear if more gas escaping into the water.

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## Zapins (Jan 7, 2006)

Sounds like hydrogen sulfide which is toxic to fish and plants. It comes from anaerobic bacteria that rot organic matter, which is one of the reasons I dislike using MGOPS (too many organics in it).

You should follow OVT's advice about poking the substrate. The idea is you want to introduce oxygen into the soil. Oxygen is toxic to the bacteria that produce hydrogen sulfide and will kill them thus stopping the production of the toxic gas. Long term, you can introduce Malaysian Trumpet Snails into your tank. They will burrow during the day time and come out at night when the lights are off. Each time they do this they pull fresh water and oxygen into the soil and prevent it from becoming anaerobic. But you need to poke the substrate first to reduce the gas, save your fish/plants, and prepare the soil for the snails.


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## HybridHerp (May 24, 2012)

+1 to having MTS at some point, I re-scaped my dirted 10 gallon and had well over 250 MTS (250 was just the amount I could be bothered to count and salvage from the soil).

I find otherwise that you are more prone to anaerobic substrate. I do like the straw idea though, gotta keep that one in mind for myself.


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## mattjm20 (Nov 2, 2013)

Thanks everyone! I will poke the substrate with my siphon (without the siphon running, because my substrate is sand...)

I'm also going to buy some MTS. I don't recall any of my LFS having them. Are they hard to come by? Also, how many would you get in a 90G?


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## Zapins (Jan 7, 2006)

MTS are very common between online forum members. I'm sure if you searched the for sale forum or posted a WTB thread you could snag a few hundred for under $10 (probably including shipping costs as well). Most people who have MTS have 1000's of them and don't care about giving them away for basically nothing.

Try get a starter culture of 50-200 snails for your 90g tank.


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## Positron (Jul 22, 2013)

There are even more ways of dealing with H2S.

Having a lot of plants with extensive root systems will help a lot. Plants transport large amounts of O2 into their roots which will help oxygenate the substrate.

Also it's possible to stop H2S from leaching out of the substrate by having a rather deep bed: also known as deep sand bed. Usually this method is used in saltwater tanks as a means to keep nitrate low. However for this to work you need 3 layers of bacteria which means you need a rather deep substrate...like 5 inches. It helps to have soil at the bottom followed by sand so o2 is deprived from the lower areas. When this happens three regions are formed: anoxic, anaerobic and aerobic. If things go according to plan the anaerobic and aerobic regions will convert the H2S into sulfate which is harmless. 

A huge plus for this method is that large amounts of co2 is naturally generated.

Here's a cool picture:
http://www.wetwebmedia.com/ca/volume_7/volume_7_1/dsb/01.gif


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## OVT (Nov 29, 2011)

I get free MTS from my local PetSmart.

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## Fred Penner (Apr 14, 2013)

I use a 1 to 1 ratio ( rule of thumb) for dirt to cap. Sand is bad for anaerobic gas especially when put over dirt. I just poke my fingers in the cap a few times a week but I'm intrigued by this straw idea!


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## mattjm20 (Nov 2, 2013)

Thanks again, everyone! This board is so helpful!


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## lochaber (Jan 23, 2012)

mattjm20 said:


> I'm also going to buy some MTS. I don't recall any of my LFS having them. Are they hard to come by? Also, how many would you get in a 90G?


All it takes is a couple and some time.


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