Question on what these valves do

[CPM10V]

I had a few questions on the exposed plumbing portion of my ‘77 pool. I’d like to relocate the equipment a little further away from pool and trying to educate myself on the layout. The equipment is a simple pump & sand filter with a valve to turn on/off an aerator, one skimmer

Anyone have insight on the purpose of the two old gate valves? The pool was apparently set up for “whip” style cleaning, there are 4-5 areas that look like a mini return jet. Think one of these adjusts the flow to the whip return piping? What may the other

The piping with the offset I presume is from the skimmer to the pump? Any idea why the offset might have been used? Likely an install error?

below pic is if skimmer/piping & equipment is behind white wall area, other pic is detail of piping

 

[Arizonarob]

Most likely to turn on 2 sets of returns. Open one with the pump running and look for changes in the pool, then do the same for the other.
The plumbing on the left looks like some kind of a Hartford loop.

 

[CPM10V]

Most likely to turn on 2 sets of returns. Open one with the pump running and look for changes in the pool, then do the same for the other.
The plumbing on the left looks like some kind of a Hartford loop.

Thanks for the info. I tried to turn either one but they’re both locked up and since plastic and likely brittle I’m a little nervous about trying to force them other direction.