Posted: Fri Mar 07, 2014 11:39 pm Re: Sand Question
Silica is silicon dioxide otherwise known as Quartz or glass. With the exception of the calcium carbonate sand used in reef tanks, most sand is 100% silica.
However, devilduck is correct that diatoms need silica. They can't use the silica locked up in the grains of sand or in the glass of your aquarium, but they can probably use the fine, microscopic silica in the dust in your sand. That's why rinsing is important and probably why play sand is worse than pool filter sand. But, your sand is mostly silica.
Tobi a RES born in 2012
1 dog, 1 teenager, 3 aquariums filled with fish, snails, shrimp and a bit of algae