Superflo pump losing prime on low speed

[PoolStored]

Also, filter does not show any pressure on 1400 rpm and on 2200 , the pressure is 5, but normally should be 15

It is normal for pressure to be low on the filter when RPM is low. At 2200RPM my filter shows 5. At 3000rpm it shows 18.

For filter operations, always check clean pressure at some high RPM, like 3000. When pressure, at 3000rpm, shows a 25% rise, then backwash. Always use a higher RPM (3000) for clean and dirty pressure.