Good Friday Morning 72elizabeth, the residual amount of sand left over in the bottom is usually very clean and white, but the pool water clears up nicely.
There are two things to consider when placing the pool on your deck, 50 - 100 gallons of water is 400 - 800 pounds, and will damage the structure without reinforcement. And the drain itself would need a grate or it could be a foot or leg hazard, and with a grate you would constantly have to clear it for it to completely drain, your set up is perfect as it is, and a small amount of residual sand in the bottom feels natural on the bottom of their feet.