The ultimate clay-based substrate thread

Sarah,
The first batch of this I made was during the winter in my garage. It is really just a drying process so heat isn't important. That step is just to get the clay to a point where you can break it into aggregates of about the right size before treating with the acrylic. Of course you are welcome to come over and mix up a batch in our garage anytime. Just bring some of that delicious antelope! ;-)

And Ed beat me to the mycorrhizal products. The natural soil adds two things to the mix. The first is seed cultures of arthropods (some of which might even establish), the second are the mycorrhizae. A good compost bin and a Burlese funnel can give you the arthropods, and the spores that Ed discusses would do the rest. However, I've read a bit on how these spore products are produced and there might still be a chance of introducing chytrid... maybe. From what I've read, these spores are produced by mixing natural soil into pot cultures with plants that make good mycorrhizae hosts. Then they subject the pots to some drying treatments that stimulate the fungi to produce lots of spores. Then the sift the pot medium and package it up. So if chytrid has a resting spore that can survive these treatments.... I still think it is worth the very slight risk though. Mycorrhizae help glue the clay particles together to form natural texture. The idea of this mix is that by the time the acrylic breaks down, the microbial activity in the soil will have taken over the job of holding aggregates together. I add earthworms to mine as well.

A paint mixer, the ones that go on a drill works, but it is still tough. Make sure you have a good drill as its a good bit of load. This is what I have used in my 3 batches I have made. Its not too bad to make 2 gallons or so at a time, but i would like to make a much larger batch. I have a 30gal cube id like to find time to work on and it will need a good bit of it.

I bought the lime on amazon as I was unable find the exact stuff locally. I was rather cheap so not a big deal.

One key that I have found as well is to add water very slowly as it is easy to add too much and then you end up with larger aggregates than you may want.

I currently have 2 15gals and a 10 gal with the mix and they are holding up very well, actually amazingly well. With other substrates I get dead ff build up rather quick and frog waste build up, but with this it looks about the same as the day I put it in.

Ditto what Kyle said. I used a paint mixer on a drill. A 1/2" drill is best but I've got a powerful 3/8" that does the job. Start mixing the stuff dry and pour the water slowly as Kyle suggests, while you have the drill running at a pretty good clip. Make sure you are plugged into a GFCI outlet since water and electric motors aren't good company. You want to get it just to the point where it is clumping into sand to gravel sized clumps.

Sarah, was it you who suggested a different type of lime? I picked mine up at a local hardware store. Lime is commonly used as a soil ammendment to adjust pH so check the lawn care department.

Sharp sand is just coarse sand. Play sand is usually too fine to be of much good. All purpose sand is usually okay. The sand is mainly for aesthetics since the finished product has really good drainage without the sand. I used a sample of Panama soil that Matt provided as my model and it had a few sand grains sprinkled in it. Here's a picture, the real Panama soil is on the right:

Don't quote me, but I believe hydrated lime is used to treat soils because it is more reactive and helps to bind soil particles together to improve tilth. Here's the Wikipedia link: http://en.wikipedia.org/wiki/Calcium_hydroxide

My guess is that for our purposes, either kind will work. I'll have to say that in the future I may switch to CaCO3 because it seems like a less energy intensive process to produce.

I think if you used portland, you would loose all of the clay properties which are really what we are after. The properties of the end result of the mix I'm using are that you get sand sized particles that drain freely, but when wet, the aggregates are sticky like clay. You can easily pinch them and they break into slippery clay. So they act like both a sand, and a clay at the same time. It took quite a bit of experimenting to get the mixture right to retain these properties. Too much acrylic and you might as well just use sand in the vivarium. The main purpose of the lime is actually to boost the amount of available calcium in the soil as a nutrient supplement for the frogs. I'd just be afraid that portland might be going overboard and you might wind up with a caustic mess. Of course, the only way to know would be to experiment. I do want to remind folks that the thread on redart clay substrates is worth checking out since Matt posted his recipe for pseudo-sand which is a more faithful replication of the real deal. Mine is more of a lazy shortcut.

One thing worth noting is that some of the early findings on the clay based substrates may indicated a major flaw in our keeping practices. I agree it is too early to make any concrete statements but some of the early pumilio benefits described could be the missing link to many issues with them in captivity.

I personally feel that a number of the common substrates including sphagnum are not adequate. Some time ago I switched a number of my tanks to jungle mix which has held up a good deal better than sphagnum, but the clay so far seems to be a whole level above that.

I have also tested an aquarium clay based product with rather poor results. It did not hold well and too much residue. Im sure it was a great product under water.

This is not to say other options do not work, but some of the "standards" may be less than ideal.

Here is a link to a page on rainforest soils.
http://rainforests.mongabay.com/0502.htm
The article starts out by talking about how and why the soils are poor in nutrients.

"three-fourths of the Amazonian rainforest can be considered "wet-deserts" in that they grow on red and yellow clay-like laterite soils which are acidic and low in nutrients."

It goes on and explains that the trees and plants have roots that are shallow, which help to absorb the nutrients from the top layers.

"Since the first six to eight inches (15-20 cm) of soil is a compost of decaying leaves, wood, and other organic matter, it is the richest source of nutrients on the ground."
"Many tropical species have roots that actually grow out of the ground to form a mat on the forest floor in order to more efficiently collect nutrients. These tiny roots form a network that, along with the mycorrhizae fungi, rapidly absorb nutrients."

So a question I have is: If we use these clay based soils should we also have a small layer of organic matter on top for nutrients/isopods/springtails etc?

iljjlm said:

Here is a link to a page on rainforest soils.
http://rainforests.mongabay.com/0502.htm
The article starts out by talking about how and why the soils are poor in nutrients.

Click to expand...

The article has some good information but wikipedia has an equally good cited article.

http://en.wikipedia.org/wiki/Rainforest
"Despite the growth of vegetation in a rainforest, the actual quality of the soil is often quite poor. Rapid bacterial decay prevents the accumulation of humus."

iljjlm said:

"Since the first six to eight inches (15-20 cm) of soil is a compost of decaying leaves, wood, and other organic matter, it is the richest source of nutrients on the ground."
"Many tropical species have roots that actually grow out of the ground to form a mat on the forest floor in order to more efficiently collect nutrients. These tiny roots form a network that, along with the mycorrhizae fungi, rapidly absorb nutrients."

Click to expand...

This is true but makes it sound as if the plants grow roots into the decaying plant material. This is not the case in most of the tropical rainforests. It may happen in the case of decaying trees, but for most of the floor space int he forest it is covered by just fallen leaves (and flowers and fruit depending on season). It is however very typical in other forests, particularly temperate and boreal forests (without earth worms).

iljjlm said:

So a question I have is: If we use these clay based soils should we also have a small layer of organic matter on top for nutrients/isopods/springtails etc?

Click to expand...

Actually if you read back to the inception of this concept, or even perhaps just this thread, the original idea was the leaves being present. The mineral soil was added as a way for the arthropods decomposing the plant material to get a better calcium balance (among other things). Together it is meant to better mimic a natural system. The importance comes int he soil and the leaves. The interface of the soil and the decaying leaves is an important junction. In some systems it is a fairly discrete line, other times the macroinvertebrates actually mix the two layers making it hard to say where one begins and the other ends.