What’s the second supply line?

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Lowbrow-Dizzy

Lowbrow-Dizzy

Member
Feb 8, 2022
12
Bedford, NY
Pool Size
33500
Surface
Plaster
Chlorine
Liquid Chlorine
Hi, this forum has been great! Managed to DIY open the pool and change the pump motor using the comments here. And NOW I’m starting to figure out what my plumbing does.

There are definitely two pipes supplying the pool. The larger one goes to 4 eyeball jets. The smaller pipe I can’t figure out. Closing the larger valve stops the eyeballs and water still flows someplace through the smaller pipe. How to determine where the small pipe is going?? Could it be supplying the two floor drains in the deep end?

I thought the smaller pipe might be for a pressure side cleaner. And there is one other port on the pool wall but it’s below the fill valve. I can’t tell that water ever goes through the port. If it’s the fill valve port, the filler is one of those toilet float types with such low water flow I may not recognize it by touch through the port. The port does not seem to push water out when just the small pipe from the pump is the only one active either.

Also I seem to not have any sort of waste valve. Is it possible to drain the pool by opening the filter bottom plug and leaving the pump on?

Thanks in advance.
 

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Hey Lowbrow,

Removing your drain plug from the filter will not work to drain the pool. You shouldn't use your pool pump to drain the pool, particularly below skimmer level. Many pools have a hose bib plumbed into a return line. This will allow you to drain off a couple inches of water without the risk of running your pump dry. A simple tee with a 3/4 NPT threaded connection will work. If you need to drain below the skimmer, a submersible pump is recommended.

It's unlikely the mystery line returns to the double drains if the pool is 15 years or newer. Anti-entrapment drains are required on newer pools. Some pools are plumbed with valves to select suction from or return to the bottom drains. Yours is not.

The extra line may have been for an abandoned water feature like a slide or waterfall. Venturi-style skimmers work off of return pressure from the pump. Turn off the valve, see if there is any change in skimmer action or post a photo of the skimmer with the basket removed and we may be able to help.

There is a possibility it may be used as a pool drain, but, seeing as how it's in the open position, you probably would have found that out by now.

Let's see if others have any ideas.
 
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I must have missed the part about the possibility of a pressure cleaner. Do you have any ports on the pool walls that look like they may have been used for a pressure cleaner? Photos may help.
 
You don't have a spa do you? If you have a spa, then it is likely feeding it. But I think that's unlikely since you don't seem to have another drain line. It's odd that it is a smaller size. That tends to make me think you have a feature, like a fountain or a water slide?

Pressure side cleaner doesn't seem likely, since you have no booster pump or hookup for one.

Are you sure all the return jets are fed by 1 line? Turn off one of the return lines and check all the jets. Then open it back up and turn off the other one and check all the jets.
 
Also, the port below the fill valve is almost certainly the equalization port. It is just a water connection between the pool and the reservoir for the fill valve, so that they are at the same level.
 
Rancho Cost-a-Lotta said:
Hey Lowbrow,

Removing your drain plug from the filter will not work to drain the pool. You shouldn't use your pool pump to drain the pool, particularly below skimmer level. Many pools have a hose bib plumbed into a return line. This will allow you to drain off a couple inches of water without the risk of running your pump dry. A simple tee with a 3/4 NPT threaded connection will work. If you need to drain below the skimmer, a submersible pump is recommended.

It's unlikely the mystery line returns to the double drains if the pool is 15 years or newer. Anti-entrapment drains are required on newer pools. Some pools are plumbed with valves to select suction from or return to the bottom drains. Yours is not.

The extra line may have been for an abandoned water feature like a slide or waterfall. Venturi-style skimmers work off of return pressure from the pump. Turn off the valve, see if there is any change in skimmer action or post a photo of the skimmer with the basket removed and we may be able to help.

There is a possibility it may be used as a pool drain, but, seeing as how it's in the open position, you probably would have found that out by now.

Let's see if others have any ideas.
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jedigrover said:
You don't have a spa do you? If you have a spa, then it is likely feeding it. But I think that's unlikely since you don't seem to have another drain line. It's odd that it is a smaller size. That tends to make me think you have a feature, like a fountain or a water slide?

Pressure side cleaner doesn't seem likely, since you have no booster pump or hookup for one.

Are you sure all the return jets are fed by 1 line? Turn off one of the return lines and check all the jets. Then open it back up and turn off the other one and check all the jets.
Click to expand...
Yep, all are fed by one line, and no spa. Can’t imagine there was a fountain or water feature. It’s a very basic pool and was only installed in 2017. Previous owners do not seem like the type to remove something that was broken.
 
Are both skimmer sucking water in?
Do you have main drains? If so, one of the openings in your pic runs to the main drains. The movable flap allows you to set how much water might come from the main drain if the skimmer basket gets blocked with debris. Water, seeking the path of least resistance will be pulled from the skimmers first.

Is there any plumbing that shows above the water level?

Show us a few pics of the pool - if you can feel/see water coming out somewhere, chances is that line is for a non-existent water feature.
 
proavia said:
Are both skimmer sucking water in?
Do you have main drains? If so, one of the openings in your pic runs to the main drains. The movable flap allows you to set how much water might come from the main drain if the skimmer basket gets blocked with debris. Water, seeking the path of least resistance will be pulled from the skimmers first.

Is there any plumbing that shows above the water level?

Show us a few pics of the pool - if you can feel/see water coming out somewhere, chances is that line is for a non-existent water feature.
Click to expand...
Yep, both skimmers suck water in. The one closer to the pump is noticeably stronger. There aren’t any plumbing lines showing above grade anywhere. Some photos attached showing both skimmers, the equalization port, three side lights, two drains at the bottom (that I really done understand what they’re connected to since I don’t seem to have a drain valve) and four returns.
 

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Chances are that the main drains are plumbed to one of the skimmers and then the two skimmers are connected underground somewhere.

The skimmer pic in post #7 - is that the one closest to the equipment? I think that is the one plumbed to the main drains, based on the two holes in the bottom and the adjustable flap.

The second to last pic above - show us what is inside the box with the cover. That may be an autofill or overflow drain setup.
An equalizer line is usually located directly below a skimmer opening the the pool sidewall. Sometimes that type line is actually part of a venturi skimmer.

Post a wider pic of the pool and equipment so we can get a better idea of where all items are. Also, pics inside each cover on the deck (skimmers and that other box too).

Is it possible that the other return pipe goes to the box with the open port below the water line (without a skimmer opening)?
 
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