What is the recommended pressure reading on a above ground pool with Hayward sand filter system? Is 20 too high?

I have an above ground pool and I have changed the sand in the filter (Hayward) and backwashed, rinsed and my pressure starts at 15 then gradually rises to 20 is this too high I have had to turn it off for fear it is after running for just several hours. What is the recommended pressure or the right pressure if everything is
Working properly?

My poolpump pressure starts at 10 (clean) with good cirulation then within 10 minutes rises to 25-30 and the cirulation almost stops. This happens when I bump the filter and also when I back wash. So unless I do this every 10 minutes the water stops cirulating. It is also cloudy, won't clear up, all chemicals are at correct level.
What is going on?