Is it possibly my main drain is fake?

[joshf]

Still getting to know the pool at the house I bought a couple years ago. I have a "drain" - at least a cover, at the bottom of my pool. When is that supposed to be used? I've never felt any kind of suction from it - with the pump on or off. Once my water goes below the skimmer, my pump fills with air and I can't drain any more (I'm not trying to drain now - just describing symptoms). I remember the pool inspector as part of home purchase called out that we needed to have the drain cover replaced with the anti-entrapment style (we did) - but now I'm wondering if there was any point.
Does that serve some other person that I don't understand - or is there something wrong with it?

 

[Jimrahbe]

Josh,

You will never be able to feel any suction at the main drain in normal operation..

Most likely your main drain ties into your skimmer.. If not, then it should have a valve back at the equipment pad..

Show us some pics of the pipes and valves in front of your pump..

Assuming it goes to the skimmer, nothing will happen unless you have a floating device that turns off the skimmer and turn on the main drain.. If you look under your skimmer basket and see two open pipes then your main drain is tied into your skimmer..

Main drains are almost useless to most pool owners.. Thousands of pools are out there without operating main drains and they all work just fine. I would not spend more then 10 seconds worrying about it..

Thanks,

Jim R.

 

[joshf]

Thanks - there is a picture of my setup in my other thread Help identifying thing on pipe. Three pipes go into the ground - one from the pool going to the pump, one going back to the polaris, and (slightly hidden in that picture) the return going into the ground after the chlorinator.

You're right -there are 2 holes in the skimmer. Does that mean I could somehow cap off the top and the pump would suck water from the main drain - when the water goes below the skimmer line? That could save me a sump pump rental next time I need to change out some water.

 

[Prickly]

Someone might have purposely blocked off the main drain if it wasn't possible to get it to meet anti entrapment requirements.

 

[Rancho Cost-a-Lotta]

You're right -there are 2 holes in the skimmer. Does that mean I could somehow cap off the top and the pump would suck water from the main drain - when the water goes below the skimmer line? That could save me a sump pump rental next time I need to change out some water.

If you have an active port going to the main drain, your skimmer is designed for a diverter/float valve:

The image on the right is the bottom. When cover is over the hole, your pump will pull water from the main drain. When open, it pulls from the skimmer. You can balance suction from both sources by partially covering the port.

Inside the top of the "UFO" is a float. When water level in your skimmer drops or when the basket is so full it cuts off flow, the float drops and allows suction from the main drain only. This is intended to keep the pump from running dry.

I tried to drain water below skimmer level with the diverter valve closed. It allowed air into the system and caused the pump to cavitate. I don't believe they are intended to be air tight.

 

[Jimrahbe]

Josh,

I found that the floating diverter valves were useless for me.. It was pretty spotty if they would work or not..

I would not use my pool pump to lower the water level anyway.. I would use a sump pump...

Thanks,

Jim R.