They say that you should use 1 lb per gallon of water.
answered 3 years, 8 months ago
0out of0found this answer helpful.
About 100!! haha My 6.6 Gallon tank has 4 bags in it and I don't even have a full bottom coverage. These rocks are big though; if you did a 3-4 inch thick bottom, a lot of gunk would get under them and make the tank gross.