It's the Guillotine! Valve Replacement Questions

Good Day All!

At the end of last season, just as I was performing the very final steps of winterizing my pool, I busted an old guillotine valve on my suctions side for the main drian, and was hoping to replace all of the valves in my set up since I’ll be getting out the hacksaw and PVC glue anyway.

I have 1.5 inch pvc plumbing feeding two skimmers and a main drain on the suction side. The plumbing set up is a bit old, so the two skimmer lines are joined underground near the pool wall (YUK) and come to the pump in one line. ( I don’t like this at all, but it’s an inherited configuration :mad: ). The main drain line comes up to the pad. Both lines have individual guillotine valves BEFORE they are joined in the usual way and fed to the pump. No check valves between the pump and the union.

I was hoping to get some advice about replacing the valves and perhaps updating the accessible (above ground) plumbing in the process.
Should I replace the main drain valve with another guillotine?
Should I go with two ball valves, or two Jandy 2 ports?
OR should I install a Jandy three port valve at the point where the two lines join and go to the pump?
I like to be able to close the suction from the main drain while vacuuming, as well as close the suction from the skimmers when I need to drop the water level for winter closing. Would I loose this control with a 3 port? Can I partially open the drain while fully opening the skimmer etc if I use a three port? Does the three port give me the flexibility to operate both suction lines at variable levels of flow?

What would be the pros/cons of using the three port instead of a pair of 2 ports.

Also I think I want to install a valve on my dedicated backwash line, but I think I can go with a ball valve there. This is sort of a band-aid as well as a water loss preventative. Here’s why - I suspect the spider gasket in my multi-port valve on the top mount sand filter is not in the best of shape because there is always a very very minor trickle of water coming from the end of the backwash line, so I think the ball valve would stop this until I can replace the spider gasket.

If someone here could give feed back about the suction side valves that would be great! I’d LOVE to hear some advice from those more experienced than I. I was gonna DIY, so any tips would be greatly appreciated!

Other pool stats:
IG Vinyl 12K gal
Hayward ¾ hp SuperPump
SandMaster 17” 100# TopMount Sand Filter
Offline chlorinator
2 skimmers
2 pressure side feeds
1.5” plumbing throughout

Thanks!

Spring is coming, lets open the pool!

I won't address your suction valve questions, but will the backwash valve idea. I had the same problem with a leaky spider gasket spilling water to the backwash. The pool service guy put a ball valve on the backwash exit to prevent the water leakage. Bad idea! Pressure built up in the backwash line and caused the little rubber check valve in the site glass to continuously leak due to the pressure in the backwash line. I strongly recommend replacing the spider gasket in the multiport valve. A handy pool store did if for me for around $30, considerably less than the cost of replacing the multiport valve. And the multiport valve now works much more smoothly without any leaks.

I didnt think of the 'upstream' impact of a valve on the backwash line. That's great advice Chuck...Thanks!