Hi guys. I have an inground pool with two skimmers and one drain in the deep end. I tried blowing the lines from the skimmer with a shop vac and only got a little out. I thought I might use a utility pump to pump them out, but the line from the skimmer has sharp bends and I can't get the hose thru it. I also noticed that there is what appears to be a plug in the bottom of the skimmer...does this go into the pipe from the skimmer? It appears to have a 3/4" square inset into it...if I can unscrew it, could I pump the line thru it?