Hello all! My wife and I picked up our first home which of course turned out to be more work than expected. We're yet to even be in yet but the work is surely in full effect! The pool was put in (according to permits I pulled from online) in 1974 and has 1.5" PVC: one suction and two returns. The pump was a external pump style with the brass impeller... I opted for going to a newer style over rebuilding this whole thing. I was able to find out by calling the number on the motor that it was a 1HP. The local pool peeps told me I should stick with a 1HP but a 3/4 would probably be fine, I felt like a new 3/4 would definitely keep up with a old 1HP so I picked up the 3/4HP Max e-pro. After getting it all plumbed up the flow in the pool was definitely more than before, now I can see ripples and the sand filter now shows 9psi instead of 2psi. Then comes what I think is trouble, when I plug in the vacuum you can hear the pump working harder, some bubbles then come in and through the system to out the water outlets in the pool and the PSI on the filter goes all the way down to 1 or 2 psi this is just with the vacuum hose plugged in, not even having the vacuum on it and sucked to the pool. As soon as I unplug the hose, the pump goes back to normal, all air goes away and pressure goes right back up. I don't think there is a leak in the plumbing that I did but I can't speak for any of the rest... but I don't think there is since I get zero bubbles at other times.
I started to think the pump may still be over sized so I did the little trick using the pressure of the filter and the vacuum at the pump basket to get the feet of head, and I come up with 40. When I cross that on the performance scale I should be flowing 70 gpm which I read is too much for a 1.5" line. I wish I could tell you the sand filter but I don't remember... It is tan, has the small opening in the top that takes the hex wrench and took 325lbs of sand... (XX-80 or something is the model)
Thanks for any assistance you all can provide me.