Two holes in skimmer?

[lambo]

All -

Thanks to this forum I'm making killer progress on my pool. Can actually see the bottom of the shallow end... amazing.

Now I have other questions, but the first is this: Why do I have two holes in the bottom of my skimmer? One of the holes has a plastic plate on a screw with a slot that allows it to slide back and forth, covering one of the holes completely. I also have two mystery ports in the pool, one near the skimmer, and another on the opposite side but they don't seem to do anything. Not returns or drains - wasn't sure if they were related to this.

I found another forum which I think explains the second hole, but I can't figure out exactly what the guy is talking about: http://www.poolforum.com/pf2/archive/index.php/t-9396.html

Thanks in advance for the time and help.

 

[JasonLion]

Some simmers have two holes. One hole always goes back to the equipment pad. The second hole might be plugged, or it might connect to a main drain, or it might go to an equalization port on the wall of the pool below the skimmer. Some builders routinely use the two hole skimmer and simply plug the second hole when they don't need it. Some builders plumb the main drain to the second hole so they don't need to run a pipe all the way back to the equipment pad. In this case the main drain serves as a source of water only when the skimmer basket is full of leaves, though the adjustable plate can be used to try and draw some water from the main drain all the time. In many areas commercial pools are required to have equalization ports so you can't get a hand stuck in the skimmer from the suction, but this is very rare in a residential pool.

So, several possibilities, and tricky to be sure which is the case in your pool without more information. If you have further questions, feel free to ask.

 

[lambo]

Thanks Jason. Once the pool is completely clean and clear I will experiment to see what happens when I slide the plate to cover that hole.

Perhaps a related question... when I get a bit of air in my pump it ends up shooting out of the return on the side of the pool as the pump regains prime. Makes sense, air is force through the system back into the pool. But why do I get bubbles coming up from what I thought was the main drain on the bottom of the deep end? That doesn't make sense to me?

 

[JasonLion]

If the main drain is mostly blocked it can have a substantial amount of air trapped in it. As the pump runs and the blockage in the main drain pipe shifts around, some of that air can be slowly released as bubbles. There are some other possibilities, but they are way less likely.