Trying to understand pool return/suction settings

[AB]

Hello,
I am trying to understand these 3 main valves on my system. It makes sense that spa/pool share a return, but why do they have separate suction settings?
I set one of the switches wrong and completely drained my spa, pool was flowing back into it...

Trying to figure out what should be the 'normal' setting for pool use, and the 'spa only' mode that I would use occasionally when heating it.

If possible, would be great to know what the arrows mean on each pipe. Is it the direction of the water flow?

There is also a label 'cleaner' on the pool suction. Do you have to put the lever right on it in order to make the kreepy krauly start up?

Thanks in advance for your help! Aaron

[attachment=0:2iv6ppgi]pool suction.JPG[/attachment:2iv6ppgi][attachment=1:2iv6ppgi]return.JPG[/attachment:2iv6ppgi][attachment=2:2iv6ppgi]spa suction.JPG[/attachment:2iv6ppgi]

 

[Bama Rambler]

I'm going to have to assume a little on the "pool Suction" valve since I can't see the pipe coming the bottom. But from the photo it looks like it switches the suction from either the suction cleaner port or the skimmer(s). the outlet is connected to the "spa suction" valve. That valve switches the suction from either the pool or the spa. The "return" valve switches the discharge from the pump to either the pool returns or the spa returns.

The arrows appear to be direction of flow.

If you're using the pool you would have the pool suction valve set to suck from the pool and you want the return valve set to return to the pool.

If you're using the spa you would have the spa suction valve set to suck from the spa and the return valve set to return to the spa.

If you're running the cleaner you need the pool suction valve set to suck from the cleaner port and the return valve set to return to the pool.

As you've already found out you can overflow or empty the spa by setting the valves appropriately.

I hope this helped a little.