What is threaded port on side of pool above water line?

[bc1080]

New owner here, drinking from firehose on pool stuff. Trying to figure out what this is on the side of the pool. I have had people tell me different things, one said it was an “alternate” return port (or something like that) and the pool needed to be filled to keep it underwater, but another guy said it was an optional vac/accessory fitting.
However, to get this port fully below water I would have to fill the pool so much that the level would be about 2 inches above the top of the skimmer opening (skimmer flap completely submerged).
On the suction side of the pump, there are two lines coming from the pool. One has an old gate valve, the other has no valve. Turning the valve end to end seems to have no effect on anything, pump seems to pull from skimmer regardless. The other issue is that I’m trying to recover this pool’s water and it’s currently so cloudy (can probably see in pic) that I cannot tell if there is a deep water or any other vac or lower ports in the pool. I'm trying to figure out what this port is and what I'm supposed to do with it. The prev. owners left a Dolphin bottom vacuum so I was thinking this is either the vac port or there is another one somewhere (unless they were attaching it to the skimmer).

 

[wireform]

We would need to see several pictures of the equipment pad from different angles and a description various ports the pool has for instance main drain? How many skimmers? How many returns? Does the skimmer sump below the basket have one open hole or is there a secondary one there too with a valve gizmo or is the second hole plugged shut?

 

[1poolman1]

New owner here, drinking from firehose on pool stuff. Trying to figure out what this is on the side of the pool. I have had people tell me different things, one said it was an “alternate” return port (or something like that) and the pool needed to be filled to keep it underwater, but another guy said it was an optional vac/accessory fitting.
However, to get this port fully below water I would have to fill the pool so much that the level would be about 2 inches above the top of the skimmer opening (skimmer flap completely submerged).
On the suction side of the pump, there are two lines coming from the pool. One has an old gate valve, the other has no valve. Turning the valve end to end seems to have no effect on anything, pump seems to pull from skimmer regardless. The other issue is that I’m trying to recover this pool’s water and it’s currently so cloudy (can probably see in pic) that I cannot tell if there is a deep water or any other vac or lower ports in the pool. I'm trying to figure out what this port is and what I'm supposed to do with it. The prev. owners left a Dolphin bottom vacuum so I was thinking this is either the vac port or there is another one somewhere (unless they were attaching it to the skimmer).

Could be an overflow line.

 

[Rocket J Squirrel]

Or a fill line. Maybe there's a valve somewhere nearby to fill the pool.

It's definitely not a vacuum suction port because there's no safety cover.

 

[bc1080]

Thanks for replies so far! I didn't get my subscription settings right, I wasn't getting notifications, but I think I fixed it now.
There are a couple disconnected or capped off lines back on the equipment pad, so there are various possibilities of what might have been there before. I attached some pictures I had, there is a PVC line coming out of the ground (right most pipe in piping closeup) that has a ball valve and then is capped off, so not sure what that was but maybe it's related. Also, the return line takes a rather crazy routing, so there was probably something else there before that was removed and patched in with piping.
Also you'll see there is an electrolysis cell, it's actually a salt water pool but the previous owners neglected it so much (0 salt, 0 chlorine, 0 CYA, etc.) I was told to treat and shock it like a chlorine pool until it gets more stabilized and then try to bring the salt cell back online.

There is one skimmer, the bottom has one open hole, the other plugged. There are two return jets.
Beyond that I am not 100% sure what is deeper in the pool sides/bottom because when we bought the house I didn't know what I didn't know about pools and didn't ask enough questions. Currently I can't see below about 10 inches deep in the water, but hopefully that will improve soon (we've had a few storms though so that's hurting my progress). A tech I had look at the pump earlier said I probably had a "deep water port," but wasn't sure.

At one point I started to add water to the pool trying to cover that port, I only got about half way up the port when the water went over the top of the skimmer, so I stopped there. But the water didn't seem to drain from the port, so if it's an overflow it must have a valve/stopper or something on it somewhere. I was looking at safety covers to install to the port if it was a vac line, but I agree now that is sounding less likely.

Edit:
I was wrong, not sure what I thought I saw but the skimmer has an open suction hole and the other has a plug in it.

 

[proavia]

It's not a suction side cleaner port as it is above the water line.
It may have been for a pressure side cleaner.

Get a PVC pipe plug, put some Teflon tape on the plug threads and screw the plug in flush. This will keep debris, other stuff and little kids from having access.

 

[wireform]

Are those holes on the elcrical boxes open or atleast one is with the fitting in it.

 

[bc1080]

Firstly, correction to the last post (I also edited the post for clarity), the skimmer actually only has one open port (the 2nd hole is plugged).

Now that it was mentioned, I think the tech we had out before mentioned something about "looking like it used to have some sort of pressure cleaning setup." Maybe that was part of the missing component in the return side that would route the return through the currently capped pipe to that side port to run the pressure side. That's just guessing, but I can try to open that capped line and see if it is tied into that side port. If so, I guess it could serve as a fill port, except that the equipment pad is so far from the house it's easier to just drop a hose in the pool.

Are those holes on the elcrical boxes open or atleast one is with the fitting in it.

There is a lot of sketchy stuff electrically I have found so far, I believe there was a lot of homeowner weekend hack jobs. Thankfully all those holes on the top of those boxes, even the one with a random fitting screwed in, are sealed. They are punch-outs that haven't been knocked out yet, but they are pooling with water and I plan to install plugs there.
One of the weatherproof junction boxes had a cover cranked down so hard on top of overstuffed wires that the corners had cracked off and it was filled with debris and must have been filling with water, don't know how that wasn't shorting out.

 

[jonpcar]

Could that port be for an aerator? Here is a picture of mine:


This attaches to it:

Pool Aerator - Faucet Aerators And Adapters - Amazon.com

Pool Aerator - Faucet Aerators And Adapters - Amazon.com

www.amazon.com

Mine used to be controlled by a valve at the pad similar to this “unused?” valve in your picture:



But the port doesn’t look to be quite the same size…yours looks bigger.

 

[bc1080]

Was wondering about that too, or maybe if I could actually convert the port to be an aerator. Mine looks to be about 1.5" or 1.75" ID on the threads, I will try to measure it. It also has a large surrounding ring/flange that I guess is for attaching it through the liner, and that ring is cracking around the screw holes and seems not in the best shape.

After thinking about it, I believe what the the pool tech said before was that it looked like there used to be a booster pump, so maybe that was connected to run a pressure side vac. Earlier tonight I also found an older looking Polaris Vac-Sweep in the attic (why in the attic I don't know), which looks like a pressure-side vac so that might be part of the puzzle.
However, I also tried to uncap that line you circled and open the ball valve and spray some water in there with the hose, but it didn't seem to come out anywhere and after a few seconds of spraying water a big slug of water shot back out. There doesn't look to be a plug or anything in the port itself, so not sure if the line could be blocked somewhere or is actually tied to something else.