I am wanting to know how much sand I need to put under my pool, it is 24 feet round x 42 inches deep.
A 24' round pool should have about 4-5 tons of sand under it. Remember a few pool building basics with regards to your sand. Make the bottom ring round and level and then pile the sand in the center of the pool. Build the pool, including top rails, and then spread your sand out.
If you try to build the entire pool on a base of sand you are just asking for trouble. The pool framework must rest on level dirt.
How many tons of sand will I need for a 21ft round pool? Also how many inches of sand do you recommend cover the bottom?
I would recommend using about 3 tons of sand under your 21' above ground pool. This should give you about two inches for the base and about a six to eight inch cove.
Be sure to follow this procedure when using sand for a base. Level the ground first and then lay out the bottom rails. Make sure the rails are perfectly round and then level each individual footplate. The sand should then be piled in the center of the pool. The wall should be unrolled, inserted into the bottom rails, and the pool frame assembled before the sand is spread out.
For more information about a sand base for an above ground pool see this page.
I am about to start prepping my yard for installation of a 24' round pool. What are your recommendations for the cove? Just use sand or would the foam coves be a better option?
It all depends on whether or not it is within your budget. The foam cove does serve a purpose, but is not really necessary. With just a sand cove you should have some type of berm around the outside of the pool. Something to ensure the pool cove stays in place. With the foam this is not needed.