I had an 18-foot round aboveground pool installed this year with steel walls and a 20 mil vinyl liner on a sand base. After the pool was filled we discovered a crater in the floor ~8 inches in diameter with a max depth of ~3 inches. My wife contacted the installer and they said that they would come out and fix it for free. They want us to drain the pool down to 4 inches of water depth before their visit and then refill the pool after they fix the floor. Is this a good idea? I have read on this site and others that emptying the pool is bad for vinyl liners. But age and ability are factors, so I am wondering if the fact that the liner is only a few months old and that the professionals will be starting the refilling process would reduce the risk of liner damage. Any input would be appreciated.