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When I close my pool I use these winter plugs with the blow-thru valve in them. I am looking for an adapter, fitting, hose (ect.) that I can screw onto to top of the threaded stem with a seal so I can use these plugs while trying to find a leak in the plumbing. The external threads on the stem...

So I just want to preface this thread with a shout out to the search function on this site and the great help that has already been provided by members here! My pool has been up and running for about 5 weeks now, and for some reason my water levels were dropping 1/2" to 1" per day. Fast enough...