Formula for calculating how much sand

[nah2o]

What is the formula for calculating how much sand I will need for a 75 gallon FO setup. I have a Skilter 450 and two power heads. It will be an aggressive setup. Since it seems that I can't find a Home Depot with the southdown, I will probably end up ordering some sand, so I am trying to figure out how much I will have to end up getting. Or you guys can just tell me how many pounds you have in your 75...

 

[fulcrum]

Here is a clip from one of Reef Fool's posts:
Here is a formula for sand. I believe it is a dry sand formula. The wetter the sand, the less accurate.
Length of tank x width of tank x depth of sand desired x .0579 = lbs of sand needed. (enter all meas. in inches)
for a 75 gal. I believe it would be 48x18x3x.0579 = 150 lbs to add 3". 60lbs would give you a little over an inch more sand.

 

[hookedonreefs]

I have an AGA 75, 48" by 18" footprint. 150 lbs. of southdown put a (roughly) 4" sand bed. (Keep in mind the quater circle barrier from the AGA overflow in the corner)

 

[treg]

I used Nature's ocean aragonite and their Live Sand.
140 lbs gave me a fat 4" DSB. I also have LR in there taking up some room so if no LR in yours you might be a little less. Different Sands weigh in at different weights per cubic foot so its hard to say exactly.
The formula I come up with when trying to figure out how much to buy was...
length x width x depth = Cubic Inch. There is 231 CI per Gallon and sand weighs about 10 lbs per Gallon.
So 47.5 x 17.5 x how deep you want it / 231 x 10 = how many pounds you need.