Pool Pump Cavitation Under Load

[Nashan13]

Hi guys,

I have just bought a house with a concrete in ground pool. It is a large pool at roughly 13x8 meters. The pump has been running with no problems since we moved in 2 weeks ago.

A couple of days ago I got given a new creepy crawly. It's a zodiac t3 and hardly been used. When I plug it in the pump starts to moan and the filter with the clear lid attached to the pump starts to fill with air. I make sure there is no air in the cc hose when it's put into the pool. I have tried the neighbours cc too and same story.

I thought maybe the pump was drawing too much so I drilled some holes in the skimmer fitting but as the air slowed, the cc stopped all together. With the flow monitor only reading 1.5.

Today I tried the cc attached with the filter set to rinse and this seemed to work fine.

I have come to a brick wall so some help would be much appreciated.

Cheers

Nathan

[Pool Clown]

Either that cleaner has an obstruction in it, or there is a vacuum release that your supposed to have, that you don't have connected to the end that connects to the pool. The fact that it performs the same on two pools says that the problem is with the cleaner and not the pool system(s). Go on the web and confirm that you have all the parts that the cleaner is supposed to have.

[Nashan13]

Thanks for the reply spa guru,

Unfortunately the CC is not the issue as i havnt tried it on another pool, but have tried another Creepy crawly on my pool with the same results.

As for the vacuum release, when i originally connected it the suction was way too high so i drilled some holes in the skimmer box adapter to allow some water to bypass. The cavitation slowly got a little better so i kept drilling and eventually drilled too much that the CC stopped all together. However pump was still cavitating. It makes me think it is a pressure problem somewhere in the system.

Maybe pump too large or possibly too small?

[Pool Clown]

Try your unit in your neighbors pool. Check to see what HP your pump is, and then what your neighbors is.

[stevenz1g]

Sounds like you may have an air leak in front of the pump that is only exaggerated under serious amounts of vacuum?

Do you have any valves that are only diverting all the suction to wherever you're plugging in the creepy crawly?

[Symmetrical]

I had a similar problem with Zodiac cleaner.

It appears the Zodiac pressure relief valve (called AD flow valve)  was the cause of cavitation in pool pump basket and popping in media filter. The AD flow valve's T shape has water flowing around the 90 deg. bend which caused a lot of turbulence and cavitation at low pressure (bypass) end of Tee - see picture. The turbulence and cavitation flowed up pipe into pump basket and caused more. I can't prove this theory except cavitation disappeared after removing Zodiac pressure relief valve.  (Previous pressure relief valves were inline so water flowed straight through.)

I fitted a new vacuum plate incorporating a pressure relief valve into the skimmer box. Then removed the Zodiac pressure relief valve and fitted a 40mm plastic pipe/ bends between vacuum plate to 11 hoses of pool cleaner. This stopped cavitation. I adjusted relief valve to get good pool cleaner operation.  (There are many reasons for cavitation - these were not the cause. This is how I fixed my problem.)