Intex Sand filter suction air leak or...???

[BlueCorn]

I've got an Intex 18' x 9' Ultraframe with the same filter. The local pool supply talked me into Zeolite sand and it's been working well. I added the Intex over the wall skimer. The bracket it comes with it stinks but with a little extra engineering it keeps the surface very clear.

Lately, I've been having issues with air accumulating and causing a loss of prime. I've been through every joint on the intake side of the pump and can't find a leak anywhere. I've checked the output and it's not restricted either. I've left the whole thing shut down for 18 hours to try and spot a leak; nothing.

Now, I'm wondering about the intake bulkhead. Is it possible that between the built-in screen and the adapter for the skimmer that I'm getting enough cavitation to cause what I'm seeing?

[Watermom]

BC, I'm going to let someone else who is more familiar with those Intex setups help you with your question. I just wanted to say hi and welcome you to the Pool Forum!

[BlueCorn]

I had to find my answer elsewhere. It's "yes" the loss of suction is due to cavitation.

[PoolDoc]

I'm glad you were able to find an answer elsewhere, but it would be better if you'd been able to find a *correct* answer elsewhere.

Cavitation is the RESULT of flow restriction on the SUCTION side of a pump; it is not the CAUSE of a loss of flow. See the Wiki page: http://en.wikipedia.org/wiki/Cavitation

Cavitation is results when near vacuum pressures are created in the vicinity of the pump's impeller, and is NOT the same as air mixed with the water flow on the suction side of the pump.

Air in the suction lines ALWAYS is the result of a suction side leak. Possibilities range from "water level below swimmer" to "skimmer vortexing" (bathtub drain 'tornado' allowing air into lines) and to cracks in the suction lines or valves.

Helping folks with suction side leaks is not one of my priorities, but not just because we have a hard time keeping up. Rather, the problem is that suction side leaks tend to be hard to identify, even when a pool guy is AT the pump. Trying to identify them via forum posts, with no pictures or sounds (very important for suction leaks!), based on descriptions from pool owners struggling to distinguish the suction and pressure sides of their pump . . . tends to be disappointingly unsuccessful.

Just because we'd like to help, doesn't mean we've figured out how to do so in every case!

[PoolDoc]

Noticing that you are a photographer . . . if you want to create a step-by-step photo sequence of all the piping elements on your pool, from the suction connection at the pool, to suction connection at the pump AND short YouTube videos, with audio, of suction flow at the pool, and also flow at the pump, I'll take a look.

-- copyright free, or CC photos. We've got too many posts here, where OPs posted photos, got their answer, and then took the photos down, destroying the utility of the thread for later readers. I transfer OP photos to the PoolForumj Picasa account, to preserve the threads, despite OP Flickr account cancellations and vBulletin forum software upgrades. --