40lbs of sand for 46g is that enough?

[lil.guppy]

I started with 40lbs of sand and 20lbs of crushed coral. I took as much of the crushed coral out so I am guessing I currently have 45lbs of sand and some crushed left over.
When I move and set the tank up again I would like to start with 40lbs of fresh but is this not going to be enough sand?
Also, can I place the rocks on the bare bottom and then put the sand in?

 

[spanko]

In a tank 48 x 12 for a 2 inch bed you would need 47 lbs. of aragonite at 70 lbs. per cubic inch.
Do place the rock on the bottom and then back fill with the sand. Will help keep from burrowing animals causing a landslide.

 

[lil.guppy]

I guess I am back to the store for 2 more bags.

 

[maryg]

I hear the rule of thumb (unless you are going for a deep sand bed) is one pound per gallon. I have 180 lbs in my 180 and it gives me 2-3" of sand. And yes put at least some base rock directly on the glass for your diggers.

 

[spanko]

Here you go
http://www.garf.org/calculators/SandBedCalculator.asp

 

[maryg]

Well being that your 46g is probably is a bowfront I would only assume that you would need the 40lbs and maybe and additional 5 or 10 lbs. if you go by the calculator.
IMO I think the 40lbs would be enough. It is a matter of preference of how deep you want your sand bed. I had 40 lbs. in my 55 gallon and it suited me fine.

 

[lil.guppy]

So what are the pro and cons of a deeper or shallow sand bed? Mine is pretty deep right now and it just looks terrible on the sides even though I have sand sifting clams and all.

 

[maryg]

I hear that deep sand beds are 6" or more. It has more biological filtration with a deep sand bed.