Had problems with previous system not wanting to prime after having to be turned off for various reasons. Replaced 1 1/2" underground line with 2"; replaced Jacuzzi 300lb sand filter with Hayward 300lb sand filter; and replaced Jacuzzi 1hp pump with a Hayward 1hp super pump for my 16'x32'x22,000 gal in ground. Still face the same problem periodically. PLEASE tell me what I may be missing. Thanks