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.