Cavitation?

[RebelBob]

I have 2 skimmers and a main drain. I was planning to do my own closing in the fall using the main drain to bring the water level down below the skimmers. However I just now tried running only the main drain and I get lots of bubbles/turbulence in the pump basket. Otherwise, with the skimmers and the main drain open there is no air and I hold prime.

After watching the cavitation video it looks like that to me. Am I missing anything? Is there a way around this by somehow pulling from skimmer(s)?

 

[Jimrahbe]

Bob,

More than likely your main drain is either plugged on purpose or it clogged with something.

We don't close in the winter, so Main drains are almost useless down here,

For closing I would use a small sump pump or you can even use a garden hose and gravity... Like you did back in the day when you used to steal gas from your neighbor's car..

Thanks,

Jim R.

 

[RebelBob]

Thanks. What about a vacuum hose? I don’t have one so I don’t know how they hook up etc.

 

[Jimrahbe]

Bob,

Most vacuum hoses hook up to a dedicated port in the side wall of the pool, or to the hole in the bottom of the skimmer, if your pool does not have a vacuum port.

I have always had problems running a big pump using just the vacuum hose.. The pump can just not suck enough water just through the hose.

Thanks,

Jim R.

 

[RebelBob]

Thanks!
Pump runs fine with only one skimmer
and main drain on so then maybe that one skimmer could be on the vacuum hose?

Thanks again for your help!

 

[JamesW]

I suspect that the main drain line probably has a small leak that is not obvious until you put it under a lot of suction.

You normally cannot see cavitation.

 

[RebelBob]

That is interesting, because I know the Jandy 3way valve on the main drain has one of its screws stripped in the plastic body. Maybe that is it? I have avoided messing with that since it works so well otherwise.