I recently purchased and Intelliflo 810 and had it professionally installed (it is connected to a Hayward DE Filter). When first starting up and running at 2350 RPM, the pressure at the returns is great. After a few days, it is barely a trickle. I've cleaned the grids numerous times and that seems to help for a while, but I still see the same issue. If I backwash just for about 10 seconds and then filter as normal, the returns have pressure again. I've run a day or so without the grids and the flow seemed to hold, but I didn't go over multiple days. The pressure at the filter looks good typically, between about 9ish to 15ish over the course of a few days.
I'm trying to decide whether it's an issue with the filtration or the pump installation--I have never had this issue before this pump was installed, but I can't prove it was due to that or just a coincidence and I'd prefer to to have the installer come back out unless I have something tangible or have at least exhausted all my options. Is there anything else I can do to troubleshoot? Am I missing something obvious?