Please ID valve!

[jets521]

Hey everyone - first time I've been on TFP since last summer (my rookie year as a pool owner). I'm very thankful for this community!

I made it through the whole summer last year without actually knowing what every knob does on my equipment
Can someone enlighten me on my pump setup

30K Gallons - IG, vinyl liner (Brand new woot!)
Sand filter

- on the white pipe (left to right) the labels are drain, east scupper (skimmer), west scupper. I have no idea what that fourth valve could be. Label was gone when i moved in. Any idea?

Any other insight into this setup would be greatly appreciated!

 

[ajw22]

Those four valves are for your drains and skimmer suction. You need to take inventory of what your pool has and see what suction is unaccounted for in the labeled 3 pipes.

If you want help post detailed pics of your pool and we will see what we can spot.

 

[Jimrahbe]

521,

Pump inputs are generally...

Main Drain
Skimmer(s)
Vacuum Port
Spa, which I assume you do not have.
Water feature - very unlikely.

Thanks,

Jim R.