Frank Andermahr wrote: > > They sell a "Medium Aquarium Gravel" (snip) Also says it contains > silicates (if that matters,I dont know) about $10 per 100lb sack. Hi Frank, The silicate content matters only if the gravel is used for sand blasting, because of silicosis danger. In a freshwater aquarium silicates are one of the "good guys" - they have low solubility. Best, George