I have a 6'L x 2'W x 26"h i am wondering how many pounds of sand it will take to have a good 1.5"-2" depth. Another question i have is the tank used to be a salt water tank and the owner painted the background (on the inside of the tank) black and white and it's not to my liking. So if there is like and aquarium safe paint or something i could use to cover it up? Thanks