weak water jet flow

[Needy]

I have a Hayward 244 sand filter, worked fine for years. this year when it is in the filter mode I have strong water pressure in the jets for about 30 minutes and then it drops significantly. When I switch to recirculate it runs great without dropping pressure. I have checked for suction side air leaks, found one and repaired it, and replaced the sand. the lateral assembly look good. I saw a post on a similar problem but with a cartage filter. I don't know what to look for next. My local pool supply store does not have any suggestions. I know this is a common problem but I could not find it. Thanks in advance for any help offered.

 

[RTamanda]

Have you backwashed & rinsed?

 

[Needy]

Yes also replaced the sand. Pressure is normal. My confusion is i would think it is a suction side air leak, but why would it just show up on filter and not recirculate. Plus i have checked every connection and no of air leak was found.

 

[Lake Placid]

Have you opened the mpv and checked the spider gasket for any failures? A failing spider gasket can allow water to bypass the filter causing a drop in pressure.

 

[Needy]

Have you opened the mpv and checked the spider gasket for any failures? A failing spider gasket can allow water to bypass the filter causing a drop in pressure.

Thank you. I just did that on your recommendation, replaced the diverter and gasket. So far it is working great. I was at my wits end trying to figure it out. Thanks again

 

[Lake Placid]

Thank you. I just did that on your recommendation, replaced the diverter and gasket. So far it is working great. I was at my wits end trying to figure it out. Thanks again

Glad to hear it worked out.