# Air Pockets in Substrate - Killing My Stuff? (pic and vids)



## cah925 (May 18, 2007)

You have a real thick layer of fine particle sand. What you are probably experiencing is pockets of anaerobic gas caught in the substrate. The gas being released can be toxic and could potentially harm your fauna. One easy way to avoid this situation is to add some Malaysian trumpet snails (MTS) to your tank. They move through the substrate, constantly stirring things up down there.

A short term solution is to use your tweezers (or something similar) and poke around in the sand. Make sure to do a water change either during this process or immediately after to get the harmful gas out of the tank.


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## DevinWolfe (Aug 1, 2009)

It is just over 3" thick at its thickest and most is right at 2"; I thought that was ideal. Should PFS be less than that?

Would the bacteria be creating the gas, or does the bacteria just survive in the gas? Meaning, if I get rid of all the pockets would I have problems with them coming back?

Is there some test I can do for that type of measurement? Or do I just assume that it's present because of the pockets and odor?

Also, there is only one Neon left alive now. 

Edit: Yesterday before the WC I did poke all over the bottom with a screwdriver and that caused the whole tank to stink. That is why I changed 50% instead of 25%.


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## cah925 (May 18, 2007)

As long as there is no water movement in the substrate, this will continue to occur. As the plant roots grow, they will find these areas and the gas will be released again. I think the snails are the best defense for this problem. There are always people giving these snails away for the cost of shipping. As long as you don't overfeed the fish, the snails will not multiply out of control.


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## demosthenes (Aug 23, 2008)

you really need to find malaysian trumpet snails (MTS) to stir up your substrate and make sure to get rid of all of the air pockets. once all of them are gone, then the bacteria that has built up in there will die and stop releasing toxic gasses. Until you get them (or if you cannot get them), take a stick or some tweezers or whatever you can find to stir up the sand yourself, so all of the pockets will be released. Then do a major water change to get rid of any dangerous chemicals that may have diffused into the water. Then you'll be fine. 

the reason that your fish are dying from it but you still have no noticeable problems with your water quality is that the toxic gasses being released aren't NO3, NO2, or NH3. there are many MANY other toxic chemical compounds that can kill your fish. Don't get paranoid about this, because its rare that any of them would get into your fish tank, but when fish die it isnt necessarily because of nitrogen levels. 

Another thing to take into consideration is that neons are _very_ unpredictable fish. sometimes you get an entire batch of them die off a few days after adding them, and sometimes you have all of them live for years without any major issues. it's a hit-or-miss kind of thing, common in fish-keeping. In fact, the air pockets may have nothing to do with the fact that you have neons dying. it could be "neon tetra disease" or something else.


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## DevinWolfe (Aug 1, 2009)

Will the trumpet snails be able to survive if the other snails died off so quickly? If so, how many should I get for 48" x 12" footprint?

I can't really "stir" the substrate because I have top soil underneath the sand and it makes a huge mess when it surfaces. I guess I will continue just to poke holes until I can find a permanent solution.


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## mistergreen (Dec 9, 2006)

Keep poking at it. Was there a smell to the gas?
It'll go away eventually.

Rotten = Hydrogen sulfide (anaerobic bacteria reaction)
no smell = CO2 or O2 (aerobic bacteria reaction or plants)


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## oldpunk78 (Nov 1, 2008)

i have been told that this is really common with MTS tanks. it shouldn't be anything to worry about. i've got the same thing going on in my 50g and everything is doing great with the exception of some weird anubias rotting. the gas most likely is H2S.


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## Ariel301 (Sep 7, 2009)

I have a substrate with playsand in it, and I get those pockets. It smells like sulfur when they're popped. I just gently poke around in my substrate whenever I do a water change; I haven't had any issues with it killing fish though. I understand about not wanting to mess with the substrate; I've got a layer of potting soil under my sand and I try not to dig into that at all, because it is MESSY. So I try to only stir in the sand part.


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## ralph50 (Oct 20, 2007)

Have you considered changing your substrate???

While anaerobic pockets occur in most substrates the finer the substrate the greater the problem.

My bottom layer is flourite covered with a bed of pea sized black gravel and have never seen it "bubble" but I know it is in there.


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## DevinWolfe (Aug 1, 2009)

If the problem doesn't go away very soon I am actually planning to use:
http://www.aquariumplants.com/Freshwater_Aquarium_Plant_Substrate_p/ss.htm

It has free shipping right now.

I was going to buy a 6 gallon bucket to do my 50G and 10G. I'm just not sure I'm ready to drop $80 on more aquarium stuff at the moment. The website reads that 5 gallons will cover the bottom of my size tank with 3". So I figure the extra gallon will be for my 10G.

My 10G that used the same batch of soil and sand is not having problems with die off at all, so maybe the problem is due to the larger amount in the 50G.

If I was sure that it was the substrate killing the fish and not something else then the cost difference between MTS and the substrate above would be less money than the cost of the fish that have already died. (hope that makes sense)


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## danepatrick (Jul 17, 2006)

+1 for the Malaysian trumpet snails.


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## ralph50 (Oct 20, 2007)

I see you used mineralized topsoil covered in sand.

I have never used topsoil but have read that some may actually kill your fish.

There is a list of topsoils out there somewhere.


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