# First Walstad Tank - Type of Subtrate Topper to Use



## rpb1975 (Mar 6, 2016)

Hey Guys and Gals! I am setting up my first Walstad tank (20 Gallon Long), and I have a question about which substrate topper would be best to go over the soil based on your experience. Currently, I have purchased Carib Sea Black Sand (http://www.amazon.com/Carib-Sea-ACS...457713736&sr=8-1&keywords=caribsea+black+sand) to top off the soil (planning on 1-1.5" of soil and 1" or so of a topper). That being said, would the sand work for cories and would it cause any issues? Should I use eco-complete or regular gravel instead? Which is the best method for the Walstad approach...what has work best for you?


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## Diana K (Dec 20, 2007)

Some of this is aesthetics- 
What look are you going for in your tank? 
Natural pebbles of various sizes can give you the effect of a pebbled stream. 
Sand can be fun for cories. 
You do not have to stick with just one or the other. 

In general, the larger the particles (pebbles vs sand, coarse gravel vs fine gravel) the larger the pore space between the particles, so the deeper a cap you need. Soil can work its way up pretty easily through coarse gravel, so it takes more gravel to keep the soil down compared to sand. 

I happen to like the blended look. Not totally all mixed up, but use pebbles in some areas, with a few larger cobbles, and sand in a different area. About what you could find in nature, but more concentrated. Some parts of natural streams have a more sandy bottom (usually where the water flows slowly) and some parts have more rock (especially faster moving sections). 
Granted, in nature these areas will usually be more widely separated than in an aquarium, but the fish are also more widely separated in nature!


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## rpb1975 (Mar 6, 2016)

I like your thought process...you got me thinking of a different way to do this. Use sand as more of the foreground topper and gravel as the topper farther back in the tank. I'll have to ponder this more. Thanks for the reply!


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## Diana K (Dec 20, 2007)

You can try some layouts, too. Sand and gravel are easy to separate once you have looked at the layout. 
Lay out a few sticks or something the size of the tank, maybe a box or something as a background. Then start arranging rocks and driftwood, and take pictures so you can repeat a layout that looks good. 
Add sand and gravel around the rocks and driftwood in different ways and get some ideas.


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