# How useful is aquarium sand/gravel mix



## Seadon (Mar 24, 2014)

I am guessing it's not very, but I know I'm not near the only one out there using a mixture like this in a planted tank...I was wondering what the CEC, if any, was and just all around how well it did as a planted substrate. My specific example is a 65/35 sand to gravel mix. Also I have a dojo loach and I've notice he takes the sand in through his mouth and shoots it out through his gills, is this harmful to him in any way?


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## lauraleellbp (Feb 3, 2008)

Your loach is doing exactly what he'd be doing in the wild, so no harm done.

Gravel and sand have pretty much no CEC. They can work fine as substrates as long as you are faithful and consistent with dosing the water column with ferts. Carpeting plants don't tend to fill in nearly as quickly or thickly with no nutrients in the subtstrate, but you can make it work.

I personally prefer subrates with nutrient content as I hate fooling with water column dosing. But that's just personal preference.


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## Diana (Jan 14, 2010)

Eventually the organic matter can build up under the sand or gravel and the finest organic matter (called humus) has CEC. 
However, I like to get a better substrate like one of the montmorillonite clay products. Not quite as heavy as sand or gravel, so it is a bit tricky to plant at first, but then the plants get going and root well. 
The reserves of fertilizer in the substrates with high CEC are useful because I do not always dose on schedule.


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## Seadon (Mar 24, 2014)

I'm thinking about doing the whole aqua soil bit for my 75 gallon, is it practical to do a mix of sand and aqua soil, as it is quite pricey, I would go rich with the aqua soil probably 70/30 but I would like to stretch it a little at least, or would I be better off doing beds of pure aqua soil? Also I toyed with the idea of red fluorite mixed with the aqua soil to stretch it and then putting the mixture in with my sand that is already in place, I am thinking red fluorite, because it is aesthetically what I am going for and also somewhat useful for plants.


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## Seadon (Mar 24, 2014)

lauraleellbp said:


> Your loach is doing exactly what he'd be doing in the wild, so no harm done.
> 
> Gravel and sand have pretty much no CEC. They can work fine as substrates as long as you are faithful and consistent with dosing the water column with ferts. Carpeting plants don't tend to fill in nearly as quickly or thickly with no nutrients in the subtstrate, but you can make it work.
> 
> I personally prefer subrates with nutrient content as I hate fooling with water column dosing. But that's just personal preference.



And Laura, do you think I could beef my substrate up a bit with some fluorite or laterite, or (insert more experienced opinion here) ?


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## lauraleellbp (Feb 3, 2008)

Sure. 

If you're wanting a carpet though (which I think you do, from some of your other threads?) I'd probably go with at least a partial substrate replacement.

The cheapest and easiest way would be to lay down a 1" layer of organic potting soil under 1-2" of gravel/sand/whatever-other-cap-you-choose.


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## TekWarren (Oct 6, 2013)

I'm growing s repens and hydrocotyle japan in sand without any issues...even without root tabs. I've added root tabs recently but not for these plants specifically.


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## Seadon (Mar 24, 2014)

TekWarren said:


> I'm growing s repens and hydrocotyle japan in sand without any issues...even without root tabs. I've added root tabs recently but not for these plants specifically.



Do you dose ferts in the water column, I think what these kind ladies are saying is that root tabs are less effective in sand as is any substrate focused fertilizer because the water movement is very low through the substrate and the CEC (ability to absorb and hold/transfer nutrients) is non existent. So root tabs won't help you, or me, as much as it would someone with a more nutrient rich, or nutrient absorbent substrate, or even an inert substrate composed of larger particles, such as gravel, or very coarse sand...they do still help though, that's for sure, just make sure they are closer to the plants you aim to impact with sand I think.


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## Seadon (Mar 24, 2014)

But I think with good enough water column ferts just about any plant can be grown in an inert substrate....it's a little different concept, but I have quite a bit of hydro and aeroponic experience and your roots are kept in a completely inert substrate if any at all and you can do anything horticulturally possible in those systems


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