Completely confused by plumbing. Backward check valve?

[cmcafee]

New member, new to pools.

Bought this house less than a year ago. Lots of stuff to learn (about pools and about how the previous did or did not take care of stuff).

The basics: 9500 gal gunite pool. 1.5 HP pump. Cylindrical cartridge filter. Inline chlorinator. Some leaky PVC valves (vacuum line intake). Old stuff. But it runs. Pump is roughly 3 feet below the water level of the pool). A check valve after the filter (possibly not aligned correctly - the other one says 'this side up'. I can't see it.) and another after the chlorinator. Picture attached. Questionable check valve is middle/bottom, between the two lines with PVC ball valves. I thought they were all return lines. I originally assumed each return line went to a different jet. Now I don't think that's true.
So...

Can someone explain this picture to me? All I know is this:

My regular pressure is about 26psi at the filter (new or clean filter). I've read that's too high generally. I asked the guy at the pool store about this and he thought maybe the pump or impeller was oversized. One day, while looking over the pool plumbing, I noticed that the flow arrow on the check valve on the middle pipe (union - spring type I think) on the return side was pointing back toward the filter (not toward the side going into the ground.).

Could this be right? Where do each of the 3 pipes going into the ground on the return side go? Are any of them possibly recirculating? I know if I cut off the flow to the one on the bottom (before it goes into the ground, all the jets still work. Not so the one on the Top. I have no idea what the middle one is doing.

 

[thepoolman]

If you don't have any water features, my wild guess would be return jets, dedicated cleaner line, therapy jets at a swimout. Not necessarily in that order though. You need to experiment.

Rotating the black valve 90 degrees CCW will turn off both the chlorinator line and whatever the check valve line goes to, so you can then see what the bottom line goes to. After you do that, rotate the black valve back to original position and turn off both ball valves and you'll see what the middle line with the check valve feeds. Whatever is left is what the line with chlorinator feeds (probably your return jets).

Check valves are usually not in an individual return line unless whatever it feeds is above the level of the pool. This keeps the water feature from draining back into the pool when the pump is off. The check valve after your filter is probably to keep water from pouring out when you open pump and filter for service.

 

[pooldv]

Welcome to TFP!

I have never seen anything like that. Normally the pool returns are all plumbed together in a loop from a single pipe from the pump. Other options plumbed from a pump are a pressure cleaner (usually has a booster pump too) or a waterfall or other water feature.

 

[cmcafee]

I have a little fountain a few feet away from the pool. It's not much of a water feature and has its own little electric pump in the bottom. I'm not using the thing but I can't imagine it's hooked to the pool plumbing. Worth checking though I guess. Thing couldn't be more than 20 gallons and the water doesn't go into the pool.

If there is a dedicated cleaner line, I don't know about it. Might have to do some digging around in the rocky area around the pool. There are no therapy jets. I'm not home to check it, but there's nothing else in the pool but 3 jets. I will say this. I flipped that check valve when I discovered it was pointing what I thought was the wrong way and lost 3 inches of water. I don't know where it went either. Maybe into the lake. Crazy.

 

[pooldv]

Could be a drain to sewer.