I'm considering getting an 21' round above ground pool....and installing it myself. I am handy but have back problems and the thought of digiging out all that turf grass like the manufacturer recommends and hauling all that sand in does not appeal to my discs. I have a pretty root free level lot and don't understand why I can't just lay the sand down over the grass. Wouldn't that and the pool liner over it effectively kill any grass or weeds there? any ideas.
The liner will certainly kill grass or weeds, but any irregularity under the liner or any particularly hard spots at all will make the liner more susceptable to wearing through and leaking. There could be small, sharp stones or sticks in the turf that you don't see.
My wife and I installed a 24' pool and it really was not too bad. I scraped the grass off and then I laid a thick layer of rock salt, Yes, rock salt, put another layer of sand a little more rock salt, a thick poly tarp and laid the ring, siding and then the liner. It only took two days plus one day to fill with water. That was our first and only pool and after two years it still sets fine. Just make very sure it is within 1" level.