Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Your tank is larger than the one I filled with SMS + EC.
You need 2.3 cubic feet to make the substrate 2" deep all over.
2.3 cubic feet may also be expressed as:
4000 cubic inches
17.2 gallons (American gallons, that is)
14.3 Imperial gallons
68.8 quarts (US)
Most sand and gravel weighs something close to 100 lbs per cubic foot, so you are looking for something close to 230 lbs.
Soil Master Select, Turface and Safe-T-Sorb are lighter than most sand and gravel, a 40 lb bag of Safe-T-Sorb covered a tank 60" x 16" x 2" deep. This is just a little over 1 cubic foot.
So, 5 bags (40 lb each) for your tank if you go with Safe-T-Sorb.
I think the Turface is 50 lb bags, (If you can still find it).