# expanded clay as a sub strait or filter media?



## ripit

This originally caught my attention as a filter media but I have found it can be used as or mixed in with a sub strait too. I have found very little about it in aquariums but what I have found was positive. 

for those that are not familiar with it, it is balls of clay that are baked in a kiln like tera cotta. It is substantially more porous though due to the way it is fired. the moisture causes the pellet to somewhat explode internally when firing. 

Right now starter bacteria uses it as a filter medium (earth pellets) and claims an extremely high surface area of sq meters per gram which if I am not mistaken, is higher than ceramic. While reviews of the bacteria are mixed, what little I could find on the media was good. One claimed to be able to make 80% water changes 3 days in a row without breaking the cycle (with it in the filter). Apparently plant roots can grow into it so it makes a good plant anchor. One person claimed their aquarium plants never grew better than when mixing this with the gravel. It is suposed to add oxegen to the sub-straight. 

I also heard mention that some atman filters come with it. All the info I have found about use in aquariums has been sparse but I have heard nothing negative. 


It is also has several other uses. For similar reasons to its use in an aquarium, it is often used in sewage treatment plants as well storm drain treatment plants and drinking water plants. It is used mixed with soil in planting and is very common with hydroponic plant growing. It is also used to help hold moisture in a terrarium. The best part is it is much cheaper than ceramic. 

so does any one have any experience with it or any thoughts on using it? I was thinking mixing some with the gravel and or putting some in the carbon chamber of my canister filter for extra biological filtration?


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## beaslbob

Although I do use pc select which is a baked clay, I have no experience with expanded or exploded, or air entrainied or whatever clay.

I have good experience with the pc select as a top layer in substrate tho.

my .02


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## Aeten

I'm 99.9% sure activated charcoal would be better for the filter but there's always the chance. I'm sure it wouldn't hurt. As a substrate looks like a pretty good idea.


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## ripit

Aeten said:


> I'm 99.9% sure activated charcoal would be better for the filter but there's always the chance. I'm sure it wouldn't hurt. As a substrate looks like a pretty good idea.


This stuff is basically little hard baked clay balls that are very porous. It is a different thing than charcoal. It works the same as bio balls or ceramic filter media as something for beneficial bacteria to grow on. The larger the surface area, the more bacteria can grow on it. In theory this stuff seems to have even more surface area than ceramic media. That's why they use it for sewage treatment, drinking water treatment etc., biological filtration. It's also quite a bit cheaper than ceramic. A few manufacture sites I have seen say balls ranging from 2mm to 36mm. Most of the bags I seem to see commercially available say 8-16mm (yea the bigger ones might be hard to use but it is much cheaper than ceramic).


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