Calculating sand depth?

[volitan_fa]

Does anyone know how to calculate how much sand you need to get a certain depth given the length, width, and lbs/cubic foot?
I just need the formula...I know there's sites out there to do it for you, but I need it to try putting together something.
Thanks all.

 

[teen]

click on live rock/ live sand on the button to the left on this forum, theres a calculator right there.

 

[volitan_fa]

I know that....but I need the formula, not something to do it for me.

 

[hotard]

((Length In Inches)*(Width In Inches)*(Depth of Sand In Inches))/24.69
So if you had a tank 12" * 12" and you wanted a 3" Sand bed
(12*12*3)/24.69
432/24.69
17.50
edit: width correction

 

[volitan_fa]

You mean length * width right?
And where does the 24.69 come from?

 

[hotard]

I have no clue where the 24.69 comes from...I just did a reverse calculation on their website.
I am guessing that is the cubic weight of the sand they have. This can not be too accurate, because of the the specific weight of sand depends on the elements its composed of. Some sites I have found are using 20 and some 25. swf.com uses 24.69...
:thinking:

 

[volitan_fa]

hmmm.....well I would really like to be able to input the specific weight of the sand per cubic foot.
Any ideas on the calculation for that? Should be something like L*W*D/wt. But I'm not a math-wizz. I barely passed calculus, and I'm too lazy to reverse-work it.

 

[hotard]

Yeah, its going to be
L*W*D/cubic weight of sand

 

[hotard]

I found this in another thread...it doesnt seem to match Swf.com's formula though
Originally Posted by 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.

 

[volitan_fa]

I want the input form to look something like this:
Length:
Width:
Depth of sandbed:
Weight of sand per cubic foot:

 

[volitan_fa]

haha....so i was right? WTF? Alright, well thanks all for spurring my thinking! I appreciate all the help!

 

[volitan_fa]

Ok, so based on everybody's inspiration, I've figured out the formula.
(L*W*D/1728)*(weight per cubic ft)
So, if you have a tank that is 12"x12" and want a 3" sand bed with a sand that weighs 90 lbs/cubic ft (like aragamax), it would be :
(12*12*3/1728)*90
(432/1728)*90
22.5 lbs
Thanks all!