Excuse me if this is the wrong forum for this, but this is my best guess.
My IG gunnite has a single drain and a single skimmer. There is a connected spa with it's own drain and return jets.
From reading the posts here (and briefly touched in another thread), the skimmer sump has two holes in the bottom - one is the line to the pump, the other is the only outlet for the floor drain.
The only valve for the suction side selects the pool or the spa. The only valve on the return also selects pool or spa (can cross-pump if desired - send pool water to spa or spa water to pool.
I was expecting separate lines for the drain and skimmer, with a selection valve to chose which was connected to the pump.
Is my setup (which does have the advantage of supplying the pump even if the water falls below the skimmer intake or the floor drain is blocked (no suction entrapment)) common?
Or do most pools have a valve to run either the skimmer or the drain?
Now for the Biggie:
Does the fact that the suction is accessible only from a 1 1/2" un-threaded hole in the bottom of the skimmer sump preclude the use of suction cleaners?
This rig has a 3/4 hp booster on 1" hose (looks like high-pressure garden hose) feeding a 1 1/2" or 2" female pvc fitting a foot or so below the water line. I have had enough trouble with the main pump not to want to mess with this under-whelming setup.
(pipe reducers everywhere, then a 1" feeding a much larger port is not impressing me as brilliant engineering).