Every spring when I try to top off my above ground pool my pressure tank runs dry. My next door neighbor has a much larger pool and fills his with no trouble. I've tried running the water every thing from a slow trickle, to full open. Fully open the tank will be empty in 10 min. at a very slow trickle I can go 5-6 hrs. My tank is a Welltrol 202 LTD, Any suggestions.