I am currently running a Hayward pro series S244-t sand filter (multi-port on top) with a pentair superflo 1.5 HP pump. When I am running the system on filter, I notice a sound in the filter like there is air being churned around. My pump is not sucking air, the strainer pot is clear without air bubbles and my pressure gauge is reading 19 PSI. I've noticed when i shut one of my two return lines (doesn't matter which one) the noise goes away. I switched out my jet eyes with a smaller diameter (from one to half inch) and the noise goes away as well but my pressure spikes to 26 PSI. That seems a bit high for my liking. Is this noise normal operation for these filters? Since its a top mount, I don't have a relief valve to purge with but have run the filter in backwash and rinse in order to try to clear out any air. I do have a booster pump attached to the system as well but when not in use, I have the valve on the intake side shut (its getting old and leaking working on replacing it). Anyone have any ideas or suggestions or even information on this? I greatly appreciate it!