What should I expect from my skimmer overflow drain?

falcor

Member
Jul 27, 2024
14
Virginia
Pool Size
15600
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
We recently had a heavy rain, 2 to 3 inches in just a few hours, and it caused our pool water level to get really high. The water level was about half way up the coping. The water stayed roughly around the same level (I didn't mark it) for a few hours so I eventually went out and opened the drain valve that my long blue hose is connected to to get the water level down.

One of our two skimmer baskets has a drain hole that's supposed to take care of high water levels. What I don't know is what level of performance I should expect from this drain. Some basic math says that 1 inch of water at the top of my pool, which is roughly 38'x16', is about 380 gallons. The hole is about 3/4" so I'm guessing the ID of the pipe is 1/2". Googling around I see that a 1/2" ID pipe with just gravity pressure, no pump, should have a flow rate of somewhere between 200 to 400 GPH, meaning that my high water levels should fall by 1" every hour or two which I'm not seeing. My suspicion is that the drain isn't working as it should but I'd like to make sure my expectations are correct before pushing on the pool builder to fix it.

Here's a picture of the high water level:

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And here's a picture of the current water level in the skimmer. The water level is always above the hole, but the builder explained that the pipe angles up a bit to prevent it from draining too eagerly which makes sense I guess.

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Do you know where the air in that overflow drain hole goes to?

Shoot some water from a hose into the hole and see if it drains out.

If the pipe connected to the hose is not properly sloped down water will not flow out due to gravity.
 
It goes to the gravel bed under the pool
So you have no visibility to water coming out of the drain?

All you can do is shoot water into the pipe and see how well it drains.

Raise the water level up to the hole, squirt some dye in the skimmer with the pump off, and see if it is going out the drain hole. This is inexpensive to use as dye and pool safe…

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