# Aquascaping in a walstad tank: substrate, hardscape, filtration?



## aquanick (Sep 16, 2020)

Hi there -

I'm thinking of setting up a nano (shrimp only) tank using Diana Walstad's method. I bought and thoroughly read her book, which I find most wonderful. That's precisely the concept I want to apply. Now, there are only three questions left:

1) Is there a limit on substrate height? In aquascaping, some designs require substrate height to increase up to the back (e.g. building a mountain look in the back). This can be achieved with potting soil and light gravel on top, of course, but I wonder if too much depth may create anaerobic pockets of soil on the bottom that may negatively affect its function and/or water quality. (An alternative may be to build an ascending ramp of silicone and place it on the bottom of the tank and put substrate on top?)

2) Can hardscape be placed on top of the soil/gravel substrate? I'm wondering if e.g. heavy stones may put too much pressure on the substrate and therefore also create dense anaerobic spots within the substrate that may be unreachable for plant roots and start to rot.

3) I understand Diana Walstad recommends an air bubbler in nano tanks (releasing a single air bubble at a time). A lot of youtube videos of nano tanks show no filter or bubbler at all. I'm thinking of building a 10- or 20-liter-tank and want it as low-tech as possible - does anyone have experience with the water movement requirements there?


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## hoppycalif (Apr 7, 2005)

Welcome to APC! I'm not too experienced with El Natural tanks, but I do know that you shouldn't put large stone or other hardscape on top of the substrate. That is a sure way to get a stinking black mess under the stone. And, I can't recall seeing anyone succeeding with an aquascape that involves deep substrate in some areas - "mountains", etc. The dominant feature with El Natural is the dense growth of a variety of plants.


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## aquanick (Sep 16, 2020)

Thanks for your quick reply! That's precisely what I fear - creating this stinking mess. Aquascapers seem to circumvent that with a special substrate called soil (which probably consists of harder and bigger grains and therefore allows for circulation in between them), but that's not compatible with the idea of a walstad tank. Looks like a mountain-like scape would have to be created with a silicone base, then.


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## Michael (Jul 20, 2010)

Silicone will work, or some other inert material such as stone, ceramic tile, bricks, etc. The main things to avoid are placing hardscape on top of soil, soil that is too deep, and a cap that is too deep over soil. It is difficult to keep the cap and soil stable on a sloping surface, so you need to use terraces or stones with pockets or depressions where the normal depth cap and soil can be placed.


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## mistergreen (Mar 3, 2007)

Place your hardscape first in the tank and place the soil around the rocks. That way the soil can get O2.

In a small tank, I think it's recommended to add 0.5" of soil and cap substrate, 1" total.


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## dwalstad (Apr 14, 2006)

aquanick said:


> 1) Is there a limit on substrate height?
> 
> 2) Can hardscape be placed on top of the soil/gravel substrate?
> 
> 3) I understand Diana Walstad recommends an air bubbler in nano tanks (releasing a single air bubble at a time). A lot of youtube videos of nano tanks show no filter or bubbler at all. I'm thinking of building a 10- or 20-liter-tank and want it as low-tech as possible - does anyone have experience with the water movement requirements there?


#1 for a small shrimp tank, I recommend 0.5" (1 cm) of soil plus 0.5" (1 cm) of gravel or sand.

#2 Never put rocks or wood on top of soil.

#3 In a small shallow tank, you might not need an air-bubbler. Bubbling is mainly to circulate heat and oxygenated water. Watch your animal's behavior for signs of oxygen-depletion. If fish are gasping at the surface or shrimp are dying, then add gentle air-bubbling. Remember that bacteria in a freshly submerged organic soil gobble up oxygen and that nitrifying bacteria require oxygen. Therefore, tank may need a little extra oxygen during the first few weeks after setup.


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## aquanick (Sep 16, 2020)

Thank you for all your wonderful feedback and suggestions! I will comply (specifically, place hardscape in the tank first before adding soil and sand) and once I get to set it up, will report back here.


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