Sand Choices, Crushed Coral, Etc.

[deputysheriff]

What type of sand do you guy's use in your tanks? I bought some back in 2000 when I first set my tank up but I can't remember what. I believe it was crushed coral or something like that.
This si what my tank looks like not, but eventually I want to add a variety of things and need your assitance in setting things up.

 

[lionstorm]

crushed coral and sand are quite different. Crushed coral looks more like gravel for one.
When you ask what kind of sand I'll assume you mean substrate. I have crushed coral now and its not pretty, algae blooms are killing me. I'm switching to a deep sand bed I've really heard a lot of good things about this system and I think this would be the best way to go but its up to you.

 

[tangman99]

The most popular sand is aragonite. If your fortunate enough to live in an area that sells Southdown play sand, you are in luck. If not and you want aragonite, you'll pay a little more.

 

[thomas712]

So what sand do I use to build my sand bed?
The answer here is aragonite sand. Many hobbyists have found that Southdown, Yard right or its apparent new name of castle sand ( or something like that) works very well for reef aquariums. This is due to it being calcium carbonate based, and with an excellent grain sizes makes for a good functioning sand bed. 1/8mm is very fine> 1/256mm to 1/16mm is considered silt, and less that> 1/256mm is considered clay.
Southdown seems to mostly contains very fine to silt size particles, and maybe a few larger than 1/8mm.
Other aragonite sands are available through many LFS. If it is aragonite it is good.
The trick here is to make sure that it is aragonite and not calcite sand as many different minerals have identical chemical formulas but wildly different properties. Aragonite is orthorhombic crystal and calcite is rhobehedral, scalenohedral or prismatic crystals
This means they have a different arrangement of atoms giving them different properties of density, solubility, hardness etc. They also tend to incorporate different trace elements, based on what best fits into their different crystal structures. Aragonite will substitute larger atoms such as strontium. Calcite grabs magnesium and iron. Aragonite’s properties are much more beneficial in a closed system.
It also seems that many have used Quick Crete play sand with success though it is not calcium carbonate based, but silica based instead. No this does not mean that you will have silicates in your tank.
Very Generally speaking Silica sand, lets say industrial style is a high purity quartz (SiO2) sand. Silica is a stable compound and will not leach silicates into your tank for it has no "sillicates in it. Depending on its chemical and physical characteristics, silica sand is used as glass sand, foundry sand, abrasives ..etc. Silica sand can contain tiny amounts of impurities, such as iron, manganese, chromium, calcium, or aluminum, and give the sand its color depending on how much of these impurities are contained within. So it depends on geographically where your silica sand comes from as to how much impurities it contains. If you are going to use silica sand look for white silica sand as it is much more aesthetically pleasing
Thomas