Cavitation in new Hayward Super Pump - causes (including the steps I've done so far)?

[GreetingsFromAP]

Thanks to this forum for everything I've tried so far. I didn't want to repost questions that have already been asked, but I figured there was enough unique here that it warranted asking. The bearings went on my old pump so I replaced it thinking that would solve the problem. It turns out the bearings going on the old pump was just a symptom of a larger issue. I am running the new pump sparingly right now and I do have a pool service company coming back out this week. I have a 15K gallon fiberglass pool with 1 skimmer and no main drain. I have a Hayward 1hp super pump and a Hayward C4025 cartridge filter. So it is just a single run from the skimmer to the pump.

• Significant cavitation in the filter basket remains after purging air out of filter
• I open the filter release valve and water does eventually come out, but I still hear air in the mix. I let it run for over a minute like that.
• Skimmer basket used to be sucked down into the skimmer assembly when pump was running, but now it isn't (put larger stones in the basket to keep it down. It was like this with old pump and is the same with the new pump
• Pressure out of the returns is fine for the first ~10 minutes
• I hear air in the filter not too long after and ~10 minutes of running I end up with air in the returns
• I ran a drain bladder and used a tennis ball on the other end to build up some pressure to try to clear the line of blockages. Some debris came out, but nothing significant
• I recently replaced the filters and when I tightened the filter ring initially I noticed a small amount of water leaking, but i was able to stop that leak
• There is one check valve on the suction side

Hoping it isn't a leak in the suction line underground. If it is, it is, but want to eliminate every other possibility first. I didn't see any leaks from the pumps wet side, filter, suction side check valve or any other of the associated unions. Any thoughts of what else to check?

 

[mas985]

First, air in the pump basket is not the same as cavitation. Cavitation occurs when the water pressure gets so low, the water boils. For residential pool pumps, cavitation only occurs in the impeller and you won't see it but you will hear it. It sounds like gravel is going through the pump.

Now on to the real issue. When looking into the skimmer, do you see a vortex? If the flow rate is too high and the water level not high enough, air can get sucked into the skimmer. If that is not the issue, then you likely have an air leak somewhere. But check the skimmer first.

 

[GreetingsFromAP]

I tried to sound intelligent and used the wrong term. I was originally going to say turbulence. I'd say it's more frothing than a vortex. Pool water level is not low. Just ran it again. It sounds like a lot of air in the filter housing. Not seeing any leaks in the filter though. Would a filter leak potentially be a culprit

 

[mas985]

While the pump is running, air can only enter the system through the suction side of the pump. The usual suspects are the skimmer, pump lid gasket, and drain plugs. Occasional, a broken pipe is the culprit.

Do you see air in the pump basket?