More than you asked for:
Why change from CC to SSB or DSB?
Most of us will not use crushed coral because it is a large substrate that traps the fish waste and uneaten food that has to be vacuumed before it creates nitrates, which it will anyway. Crushed coral does not provide a very good biological zone, and many tanks are setup with CC from the get go through lack of knowledge or because it is the only substrate that an LFS sells and tells you that it is all you need, using a selling point of CC has buffering power. I have personally battled nitrates over 100 ppm during my days of CC and UGF doing frequent large water changes. So many of us have been there and had high nitrates, did a water change to lower them and they were back in a couple of days. CC has sharp edges, which is undesirable for inverts, like anemones walking around, pods or worms. No getting around it CC is high maintenance and can lead to poor water quality, frequent maintenance, sick livestock, algae blooms and more.
Sand on the other hand has more benefits. These include having far more surface area thereby making it able to handle a higher bio load of bacteria. It is less dangerous to your infauna and has a more natural look in the tank. If going with a DSB Deep Sand Bed you can have other benefits as well like finishing the denitrification or providing sand sifting, burrowing, or tunneling fish and critters a place to play. The denitrification process predominantly occurs in deeper substrates and in areas of stagnant flow where oxygen levels are depressed. And this is why deep sand beds are effective as a nitrogen export mechanism. As water slowly diffuses deeper, aerobic organisms strip all available oxygen for respiration. In the deep, oxygen-deprived layers, denitrifying anaerobes are given the opportunity to convert nitrogen compounds into nitrogenous gases, which escape via tiny bubble out of the aquarium. I believe this process can also work on a limited basis in shallow sand beds. My sand bed is no more than 2 inches deep in some spots.
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 old castle sand 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
A warning about silica crystals:
Silicosis is a disabling, nonreversible and sometimes fatal lung disease caused by overexposure to respirable crystalline silica. More than one million U.S. workers are exposed to crystalline silica, and each year more than 250 die from silicosis. There is no cure for the disease, but it is 100 percent preventable if employers, workers, and health professionals work together to reduce exposures.
So in other words do not breath this dust. FYI there is also a warning label required by the state of California that is required on silica play sand.
Ways to test sand to see if you might be able to use it in your aquarium:
Take a sample of your sand and test some of the sand with vinegar. If it bubbles/dissolves, it is calcium carbonate sand and should be safe to use.
Take some sand and pass a magnet over it or in it, it might come out with little metal shavings from processing, if it does I would not use it. Though I have heard of some who have with little poor effects. Iron can actually be a fertilizer for macro algae.
So you can use the right play sand and it will be cheap, much cheaper than purchasing at the LFS.
Or you can purchase live sand which is normally made from aragonite.
Whichever way you want to or have to go depending on playsand availability.
If its aragonite then it is calcium carbonate.
Live sand means that it has the bacteria on it, not necessarily pods and worms.
Dry sand will become live sand after the cycle is completed because then it will also have the bacteria on it.
It is best to seed it with liverock, or you can use livesand from someone elses tank to help with the seeding, both can contain the benfical pods and worms.
Thomas
