# New substrate needed?



## Henry (27 Mar 2013)

Evening all,

I recently set up my high tech(ish) tank planted with H. corymbosa compact, and H. tripartita. I used an inch of bentonite clay from clumping cat litter, topped with and inch of unipac zambezi sand, and some 2mm aquarium gravel I found in the cupboard.
I'm a little concerned that the bentonite clay may be too deep, and coupled with the fine gravel, compacting may affect root health and impede my plant's growth.

I was considering taking it all out, and using hard grade Akadama instead.

What are people opinions on this? Is my current substrate ok, or will I do a lot better with something else (Akadama or otherwise)?


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## foxfish (27 Mar 2013)

Interesting mix!! uumm how about some purpose made substrate - if you can justify the cost, like ADA amazonia?


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## Henry (27 Mar 2013)

I'm trying to avoid expensive substrates. I'm on a very strict student budget! I was going to buy some Akadama, which is very similar to purpose made substrates, but without the nutrients. It still has the very high CEC, but is a fraction of the price.

I'd be willing to keep my current substrate if I knew that my plants would be able to thrive in it.

Hmmmmmm.....


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## ceg4048 (28 Mar 2013)

Hello,
	   Plant roots don't really care how deep the substrate is. They will continue to grow and seek their own maximum depth if the the plant itself is healthy. Deep substrate is never an impediment or a limiting factor in root health.

Akadama is an excellent choice as well, as demonstrated in the sticky thread in this section.

Cheers,


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## Henry (28 Mar 2013)

I'm not so much concerned about the depth itself, more what the substrate consists of and whether it is at all beneficial to growth. Having read about compacting substrates and lack of flow around roots being unfavourable conditions for roots, I've grown a little concerned about my sticky clay and fine gravel.


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## foxfish (28 Mar 2013)

Well to be honest 'bentonite clay' is a completely new word for me!!
I do know of a few folk who have tried using clumping cat littler but, it is a nightmare if ever disturbed & I am not a fan of mixing substrate anyway.
Personally I dont really like akadama as I have found it also degrades over time & makes an awful mess if disturbed, hard baked clay cat litter seems far more stable & is most definitely a tried & successfully tested substrate.


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## dw1305 (28 Mar 2013)

Hi all,
Sodium bentonite clay is the "drilling mud" they use in oil wells, and also forms the impermeable bunds around landfill sites (where I encountered it). It is very fine, and very sticky and "muddy".

My suspicion would be that the cat litter is calcium bentonite (Fuller's Earth), which would be fine as long as you don't disturb it.

cheers Darrel


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## Henry (28 Mar 2013)

Its the cat litter, yes. I did want to get some of the baked cat litter, but it Tesco doesn't seem to stock it any more. The Sophisticat alternative looks like it could be too big for my liking. Not sure what to do.


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## sciencefiction (28 Mar 2013)

It depends on the cat litter and the type of clay exactly its made of. They are different types of clay, each rich in different minerals, some rich iron like the earthenware clay, some rich in calcium and magnesium like the bentonite clays(making your water very hard)
Some are baked/fired at different temperatures. Like Turface for example, which is a baked type of clay, made from Fuller's Earth, which in turn is simple calcium bentonite as Darrel suggested) or Akadama(some sort of baked clay from volcanic origin). They are famous as aquarium substrate for their high CEC abilty and because of the preparation/baking, they don't fall apart/compact in aquarium as fast as raw clays would. 
But raw clays will do that almost immediately, so they can't be really used as a sole substrate.  They are still beneficial as an additive to soil subsrate though, as they have better flocculant abilty (aids in water clarity) than baked clays on top of  having good CEC as well.  Clays of the type earthenware and pottery clays contain iron, which is good in planted tanks and they also don't change the water hardness,  unlike bentonite clay.
Cat litter is often made of baked calcium bentonite clay, so ir may not fall apart and compact as fast, but it really depends on the cat litter type, could be either way, some even contain sodium bentonite clay which can expand 18-20 times!! So just check out exactly what it is, and consider if its a bentonite, it will change the water parameters at these amounts.
Sorry if I rambled too much


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## Henry (28 Mar 2013)

Interesting stuff sciencefiction. I didn't consider their buffering capacity, and this is something else I definitely need to consider. I think I'll have to do a pH test and see what kind of effect its having on my water. After reading about the benefits of magnesium on plant growth, I imagine the plants will be grateful for the bentonite, but I'm not sure I could say the same for my fish. I suppose I'll have to do a bit more investigation.

I remember the bag saying 100% natural clay, and its a definite grey colour. The uncertainty of it all is starting to worry me a bit. Fish have been alright so far. Finances say I'll have to wait and see


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## sciencefiction (28 Mar 2013)

There is a purer form of calcium bentonite called montmorillonite clay, although I am not sure how much the latter differs from a normal calcium bentonite....anyway its known as koi clay. Its very beneficial to fish health due to its specific mineral content and is especially used in koi ponds. It's also very good for absorbing toxins from the water, so I've read its even used in shrimp tanks to small amounts(not to alter the water hardness)


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## sciencefiction (28 Mar 2013)

To add to calcium bentonite/montmorillonite clay topic, the difference between the two is mainly that bentonite clay isn't tested for all types of stuff it contains, so it maybe richer(or not) on some unwanted type of metals like lead for example, where pure montmorillonite clay is supposed to be "purified" and is used not only for fish, but humans too.

Another baked clay famous aquarium substrate I can think off now is seachem fluorite.

Chances are your fish and plants will be perfectly fine, especially if the types you have can adapt to harder water. The problem is it may eventually fall apart and make the water cloudy, may compact a lot too, but that depends on your plant types as well and whether your cap can hold it down instead of sneaking through the particles and invade the water column.


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## Henry (28 Mar 2013)

The fish seem fine, thus far. The water is crystal clear, and I imagine due to how the fish are doing, it doesn't contain anything harmful. I was, however, concerned about the compacting and the effect it could have on the roots.

I'm growing H. corymbosa and polysperma, Cryptocoryne crispulata var. 'Balensae', and Hydrocotyl tripartita. Not sure if this is consequential.

I'm pretty tempted to get some Sophisticat Non-Clumping and cap it with some fine gravel.


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## sciencefiction (28 Mar 2013)

Probably non-clumping is better for plants. Clumping will clump  and I have no idea to what extent. the H corymbosa and cryptocoryne have good root systems and if your tank is fairly well planted, may prevent some but who knows..
I wouldn't mix sand and gravel as a cap too, if the sand grain is too small the gravel will settle on top and the sand will act as additional middle layer preventing oxygenation of the bottom clay layer. The effect would be anaerobic substrate, hydrogen sulfide, possibly rotting roots and plants not thriving, but that all depends and there are tanks that defy all rules and thriving regardless.


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## Henry (28 Mar 2013)

The anaerobic spots worry me. The tank is packed to the hilt with plants, but this still doesn't stop me thinking. The non-clumping is baked moler clay, so will be great for plants. I'll just have to find out what the grain size is.


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## Henry (12 Feb 2017)

Well, here I am again. This time I'm making my own root tabs.

My question is this: how much of the bentonite clay can I add to a 600L tank without upsetting the parameters too drastically? It's going to be a discus setup, and the substrate will be around 6-8 inches deep where Echinodorus will be planted.

I have made 1" balls using the clay and osmocote.


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