I've got a problem with my in ground pool filter and pump pressure.

I changed the sand last fall. This year when I run the pump, it will start at around 15-18 lbs of pressure. Then it will gradually rise to about 35 psi.

I've backwashed several times and rinse the system each time. It will be good for maybe 10 minutes then climb right back up to 35 psi.

I notice it the worst when I'm trying to clean the pool with the vaccuum.

Oh yeah, I did change out the inside valve gasket on the selector.

Thank you
Rumple

The problem may be in the sand mix, with most probably too many very tiny sand grains that slowly block up water passage through the filter. Try replacing the sand !

Success !

Do you mean the sand is maybe to fine? So I need to find a coarser media?

Thanks
Rumple