I bought a home with a small pool and it has 6 return eyeballs but they are slit type and were directed various directions so the water did not circulate well back to the single skimmer. I want to buy 6 new ones but plan to get the actual round opening eyeballs. The openings come in various sizes from 3/4" down to 1/2", 3/8" and perhaps smaller. I used to have a pool with only two 3/4" eyeball returns. So I wonder if with 6 returns I should use a smaller opening and if so what size anyone out there would recommend.