30 PSI on Filter, no pressure in returns and pump will not prime

Hi,
We currently have an inground pool with a Hayward Perflex EC75 DE filter w/a 1.5 hp pump. We only have the skimmer basket and two return lines. We took the filter apart to soak the fingers in filter cleaner and put it back together. The pump will not prime on its own, what I have to do is put the filter in backwash for about 20 seconds to get the basket to fill with water and then put it back to the regular filtration mode. After it runs for a bit I start to see air accumulate in the pump basket (around 30 min, starts out with small bubbles and then just gets bigger but not to the point we have to turn it off and reprime).

Since we have cleaned the filter we have gotten semi good pressure coming from one of the return lines and hardly anything coming out of the second line. However I have seen both lines bubbling. Before we cleaned the filter there was hardly any pressure coming from either of the return jets. The skimmer basket doesn't look like it is doing anything either.

The pressure on the filter shows its at 30PSI (new gauge, just installed it yesterday). It stays at this level, even with the vacuum hooked up to it (which the vacuum isn't operating properly either, not getting the suction it needs, it will pick up some of the little things but not leaves). I am going to replace the seal on the basket tomorrow even though it doesn't appear to be bad but just to rule it out. But I guess my question is this indicative of an air leak or could it be the filter.

The reason I am thinking it could be the filter is because before we cleaned it there was hardly any pressure coming from either of the return lines and vacuuming wasn't working. And the pressure being so high on the filter worries me. The filter according to the pool guy up the road is old. It a yellowish manilla color and he said Hayward started making that model about 30 years ago. We also took apart the pump yesterday to make sure there was nothing caught in the propeller things on the motor. Is there a way to rule out the filter as being the issue. Or does this still sound like a suction air leak. Backwash works fine and when we opened the pool I cleaned it on backwash and didn't have an issue with it picking up debris.

Oh and the water is clear now. Any ideas on what would cause this? Would we get 30 PSI on the filter if there was an air leak?

Thanks!

30 psi is close to the shut-off point on many pool pumps. That's a strong indication of blockage, downstream of the gauge. The blockage could be in the filter, or the piping.

Have you disassembled and cleaned the filter this year? If not, you should.

Here's the Hayward Perflex page and manual

Read this page,

cleaning-a-DE-filter

before you tackle that project. The Perflex is a bit of a bear to disassemble.

Good luck.