Filter not filtering - Water returning to Pool in "drain" mode - water cloudy ... is it the valve or something else


May 10, 2020
Ottawa, canada
Hello all,

Bought a house with a pool last fall, filter was working fine then. Somebody else closed the pool for winter.
Started up everything this spring, did the pookl shock and all but filter is not filtering. When I put the filter in "drain" mode, water is returning to the pool as well as coming out of drain pipe (for backwash). From what I understand from the manual, this should not happen.

After more than a week of filtering, pressure never goes up on pressure gauge yet water remains cloudy and dirty.

Is the valve the issue causing water to bypass filter altogether ? Is it worth replacing ? How can I know for sure it's the valve, I don't want to embark on replacing part A, then Part B, then Part C and so on.
I've put an order on a new hayward cartridge filter but due to COVID, there are delays and I'm growing impatient (probably due to abnormally hot weather this past week for this time of year :) ) and I'm starting to wonder if I should not fix the old filter in the meantime.

Thanks in advance for the help.