# River sand as substrate



## tighidden (Jan 16, 2010)

Does anyone know if river sand would have nutrients in it (Fe, Mg, Mn, Zn etc.). Also if anyone has had experience using river substrate I'd appreciate any input.


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## Diana K (Dec 20, 2007)

'River' is not a scientific definition of sand. 

Put some of want you want to use in a jar of water and test the water with all the aquarium tests you have. 

Sand (soil science definition) is a particle size that is too large to have any cationic exchange capacity. 
The particle might be degraded rock or other material, and if the parent material had any of those minerals then the sand will have them. But are they doing to become available to the plants in any sort of dose that will be helpful to the plants? 

If the material you are using is actually finer than the strict definition of sand, if there is any clay in it, then there is some cationic exchange capacity, and the clay might have some minerals associated with it. Also, when you put it in an aquarium and start dosing, the clay will remove some of the minerals from the water and make them available to the plants' roots. 

Anything from a fresh water source used in a fresh water aquarium has the possibility of introducing diseases or parasites to your fish and plants. I would suggest at the very least rinse it well to remove organic matter and then spread it to dry in a very sunny place. Let the dryness and the UV in the sun's rays kill the possible pathogens.


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## medicTHREE (Feb 5, 2010)

A quick way to kill anything in sand is to bake it. 400 degrees for an hour will do the trick. Less likely is fine. That being said, I have used loads(literally hundreds of pounds) over the years without so much as rinsing it.


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## tighidden (Jan 16, 2010)

Well thanks for both the posts they were very helpful. I liked the technical response Diana K ;-). Also where I am from the soil has large amounts of clay in it. The "sand" is reddish in color, does that hint at the possibility of there being clay in it, or is there really no simple way to tell?


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## Diana K (Dec 20, 2007)

To find out how much sand, silt and clay is in a particular sample of soil (by any other name...):
Make sure the sample has no clods. This may mean grinding it in a mortar, but pounding it a bit with a hammer (lightly) may work, too. Don't get too aggressive. Just some light taps. Remove visible organic matter (sticks, leaves)

Put some masking tape, or other tape you can write on onto a jar with straight sides. (Jar volume might be anywhere from 1 cup to 4 cups. 2 cups is just about right, but any volume will work)

Put the soil in the jar, and tamp it a bit to get out the largest air spaces. Mark where on the tape is the top of the soil. 
Add water to pretty much fill the jar, at least more than the soil, and a tiny bit of detergent such as dish washer or laundry stuff. Less bubbles is better. 

Shake REALLY well. Shake some more. And some more. (See why a somewhat smaller jar is better than the jumbo sized jar?)

Set the jar on a table and start watching. Floating stuff is organic matter that has not absorbed enough water to sink, yet. The stuff that falls out in the first 30 seconds is sand. Mark that level on the tape. 
By about 2 minutes most of the silt has settled. Mark that level on the tape. 
A couple of hours later the coarser clay particles have fallen out of the water. Mark that level on the tape. 

How to interpret the results: Measure the amounts and compare to the dry measurement of all the soil. 

Sand up to 75% is OK in an aquarium. 
Silt for most of the remaining 25% is pretty good. These numbers could go plus or minus perhaps 5-10%. 
Clay over 5% is too much for an aquarium. 
If the water is still cloudy after 2 hours the sample has too much coloidal clay. These are particles that are so small that Brownian motion keeps them suspended. Do not use this material in an aquarium.

Color has nothing to do with particle size.


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