i know many FW hobbiest use that $30 50lb sand from home depot. can that stuf be used for SW? it's that mason sand(silica). can it be used more for FO set ups?
1. The “silica” play sand that I purchased from Home Depot can substantially raise the dissolved silica concentration in seawater.
2. The dissolvable portion of the silica sand cannot be completely removed by several rinses with either fresh or salt water, although it may be decreased somewhat by that process.
3. Southdown calcium carbonate sand (likely aragonite) can release soluble silica, but about ten fold less than the “silica” sand.
Is it OK to use silica sand? Probably. Many people do so. I also believe that not all “silica “ sands will be the same for the reasons described above relating to processing of the sand and the nature of the mineral inclusions present. So the fact that many people successfully use some (or many) types of silica sand does not necessarily imply that all people can use any type of “silica” sand without a problem.
Actually the answer of no silica based sand has been reversed on reefcentral as per Randy Holmes-Farley. He actually doses silica now in his tank. Because you can no longer get Southdown (or any silica free sand at homedepot,etc) many people have been adding the silica based sand by yardright or Kolorscape. These bags are about $4 per pag for 40-50lbs.
Personally I had a DSB of Southdown and when I replaced %50 of my sand I stuck with Aragonite based sand for look and feel reasons.