Hello I have a 15x30 AG pool with 1.5 piping. The pump is located away from pool with pipe running underground. It drops 1.5-2' below pool and is 40' of pipe away both return and supply. I have 11. 90's, 4-45's and sand filter, a UV light and will add a heater later. I have the 1.5 HP pump that came with it on it now. The water is not flowing enough to keep dirt from dropping to bottom or have surface items flow to skimmer. What size and model of pump will I need?