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Sand is sized according to how it falls through a wire mesh called a sieve. A pile of sand does not have only one grain size but it has a distribution of sizes. To size the sand, it is shaken through a series of progressively smaller sieves that are stacked on top of one another. The sand that falls through a mesh is is given the designation of -size (e.g. -8). The sand that remains on top of that mesh is designated as +size (e.g. +12). Most of the time the -'s and +'s are left off and the top and bottom sizes are simply shown as 8/12.
For various industrial applications there are different standards that say what series of sieves are used and what percentage of sand must be in each sieve to be a given size (e.g. 6/8). As the application gets less demanding the description of the sand becomes less rigorous. Common industrial sand is typically described by a single number and here in Oklahoma, the common sizes are 4, 8, and 24 mesh.
The sand that George Booth uses for plant tanks is a 5/15 sand (according to the archives), but that seemed a little fine to me and I went with a 4 mesh sand. You can look at the table below and see for yourself what size you want. You can buy common industrial sand in any metropolitan area by looking in the yellow pages under sand and/or gravel and calling around. The cost should be about $5 per 100 lb. in the US.
I have seen references to sandblasting sand but I was unable to locate anyone in my area who sold it in the sizes I was looking for, so I don't know if the table below applies to that type of sand. Of course you should test the sand before using it in your aquarium to see if it changes your pH (see the FAQ and the Krib for info) and wash it thoroughly.
|Nominal Size (mm)||Open in.||Open mm|
* There are some minor variations in the sizes according to which reference is used.
Hope this helps,
Harold G. Walters
hgwalters at halnet.com
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