Estes Spectrastone Blue Gravel by Estes Sold out $26.02 select a variant 5-lb - Translation missing: en.products.status.sold_out 25-lb - Translation missing: en.products.status.sold_out select a variant 5-lb 25-lb Title 1 2 3 4 5 6 7 8 9 10+ Quantity Quantity Sold out Spectrastone blue gravel is an ideal substrate for fresh water and marine tanks. Our standard colors use silica quartz which is an inert stone that will not affect pH.IngredientsN/A