Can't figure out my plumbing

[jkatID]

Thanks in advance for any help. I moved into this house earlier this year. I am trying to figure out the plumbing. It is a large pool about 40k gallons. I have 2 skimmers with what appear to be vacuum ports just below them. There is a valve in the grass near the pool which looks like a control for main vs skimmers. There is only 1 line coming into the pump (no additional valves). I don't see any other valves.

I am trying to figure out how to turn on the vacuum ports and adjust the skimmers.

 

[Texas Splash]

J, I suspect the the port below the skimmer may be an equalizer port, although it appears the fitting is missing. There may also be a diverter/float valve in that skimmer which allows you to adjust the water pull from that port. In pic #3, the valve missing its handle looks like you can pull water from the drain or skimmer(s) only. Unless there are other ports or valves not shown, you may have to use a manual vacuum by utilizing a vacuum plate in the skimmer or just inserting a vacuum hose directly into the skimmer hole.

 

[1poolman1]

Thanks in advance for any help. I moved into this house earlier this year. I am trying to figure out the plumbing. It is a large pool about 40k gallons. I have 2 skimmers with what appear to be vacuum ports just below them. There is a valve in the grass near the pool which looks like a control for main vs skimmers. There is only 1 line coming into the pump (no additional valves). I don't see any other valves.

I am trying to figure out how to turn on the vacuum ports and adjust the skimmers.

Ports below the skimmers could be equalizer lines, not vacuum lines, if the main-drain is plumbed separately through that valve. They allow the pump to still get water if the level in the pool drops below skimmer level.
You need to turn the valve with the system running and see the effect.
There may not be a way to adjust flow from the skimmers individually if there are no other valves.

 

[jkatID]

OK thank you I didn't know about equalizers. I attached a pic of the inside of the skimmer. I thought the extra hole was to the main drain.

 

[1poolman1]

OK thank you I didn't know about equalizers. I attached a pic of the inside of the skimmer. I thought the extra hole was to the main drain.

Hole in the bottom of the skimmer closest to the pool is probably plumbed to the port below the skimmer. Hard to tell what skimmer that is with the water swirling, but there was probably a float-valve in it when new. Looks something like this:

They are not universal, but brand specific.
This video explains the use: