After years of successful TFP maintenance of my AGPs, I'm pretty much taking over care of an in-ground pool about 30 miles from my house. So please be patient as I will probably ask a bunch of newbie questions all over again.
The pool has a skimmer and bottom drain but only 1 pipe coming out of the ground to the pump inlet (I was expecting 2 lines plus a valve).
The plumbing looks like this:
There are two holes at the bottom of the skimmer but it seems like only 1 of them has suction (I think), I'm guessing that is normal. Sitting at the bottom of the skimmer is this thingy. Does this normally provide some kind of adjust-ability as to how much suction comes from the skimmer vs. bottom drain? Also, does it allow me to drain the pool below the skimmer without sucking air so i can adjust the CYA level? Any inputs would be appreciated!
That thing is really stained, but probably can't be cleaned. The inside of the skimmer looks the same.