Eyeball return jet...correct sizing

[ddpool]

My original eyball fitting needed to be replaced. I opted to go with the 1" return size....well after installing I noticed the pump making much more of a cavitation sound. After research I found that you need some back pressure on the return line. So, I put my hand down in front of the return and presto the noise went away! My question is, do I go with the 3/4" or the 1/2" size? Is there a correct size? Can I do damage by putting the 1/2" fitting on there? I think the 1/2" size would really quiet the cavitation sound. Thanks in advance for any suggestions.

 

[Guest]

Cavitation would be air in the pump, but you say this is on the return side. I'm not sure why this would cause you to get air in the pump. Sounds like you have a leak ahead of the pump somewhere.

 

[Bama Rambler]

I assume that you only have one return and that being the case, I'd go with a 3/4" eyeball. You won't hurt anything by using a 1/2" it just won't allow nearly the water through that a 3/4" will and that'll increase your turnover time significantly.

The most probable reason for the cavitation is restriction of the suction piping. It could be the skimmer or the piping itself.

 

[ddpool]

Thanks for the replies. I put a 3/4" on and there is still slight "noise" (less than the 1")...when I put my hand down in front of the return and push against it...the "noise" goes away and the pump runs virtually silent. So, I am guessing that my 2hp pump needs some back pressure on it or it is pushing water out too fast. My skimmer is clean and operating normally with standard hoses...interesting. btw...I do have just one return and one skimmer.

 

[mas985]

Probably what you are hearing is water noise in the pump and plumbing when the flow rate gets high. Using smaller eyeballs should fix this. Are the pipes for the suction and return lines the same size/length? Also, what is the filter pressure with the 1" vs 3/4" eyeballs?