# Substrate for Walstad Tank



## rehdjac (Apr 9, 2008)

I'm having trouble figuring out a substrate to top the soil in my new tanks. I bought a bag of "pool filter media" as I've seen illustrated on this forum, but is looks much more like sand than the example I saw in the sticky.

I also bought a big bag of #16 silicate sand from a local building supply. Both were dirt cheap, but I've been told that sand is problematic for these tanks?

I appreciate any advice you can give me.

Thanks much!


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## cs_gardener (Apr 28, 2006)

If the sand is too fine or the layer is too deep it can cause anaerobic conditions to develop. What is the average grain size of what you have? You're looking for something about 2-3mm in diameter. 

I've never used pool filter media or sand but I know others here have with good results. For my tanks, I had a lot of leftover Eco Complete from when I first got started and reused it as a top layer over soil. I've also had good results with Soil Master Select (SMS) as a top layer, and it's a lot cheaper than Eco Complete. I use about 1-2.5" to top the soil, depending mostly on the size of tank and what I plan to plant. It would look kinda silly to have 3+ inches of substrate in a 10 gallon tank after all.

You can get Malaysian Trumpet Snails (MTS) to help stir up the top layer to minimize the risk of it compacting and the substrate turning anaerobic.


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## rehdjac (Apr 9, 2008)

Ok thanks.

Took the silicate back.


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## landlover (May 5, 2008)

I am curious as to way one couldn't just use the soil alone. Is is because of silt stirring up or is there another reason. I am in the process of getting a second tank and plan on using the Walstad method for it. I don't want gravel so I can get the most natural look possible. Thanks.


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## Dustymac (Apr 26, 2008)

landlover said:


> I am curious as to way one couldn't just use the soil alone. Is is because of silt stirring up or is there another reason. I am in the process of getting a second tank and plan on using the Walstad method for it. I don't want gravel so I can get the most natural look possible. Thanks.


I think you're right. The fish and snails poking around the bottom would cut down on your water clarity. The gravel simply serves to keep the water clear once it has settled down.

I guess if you wanted a really natural look, you could head over to your local stream and dredge up some gravel from a sand bar, assuming you live in an area with the right geology. You'd need to wash it really well to eliminate any toxic deposits. Then you'd need to test it under water for a week to ensure it wouldn't leach out anything that would adversely alter ph or hardness. Then, to get out all the fine sand which could cause compaction of the substrate, you might want to sift it through some window screen. To get out any large rocks, you could sift it through some 1/4" hardware cloth.

Hmmm.... I'm kinda liking this idea! I'm going to try it. Thanks for the inspiration! 
Jim


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