Swimming pool main drain - how to tell if its pulling water?

Question

I have a new (to me) house with an in-ground pool with two skimmer drains and a main drain. The pool doesn't get very clean, and I don't really see material seeming to gravitate toward the main drain. Should all of the water intake be done via the skimmers, or should the main drain be pulling as well when the pump is on? How could I test for sure? Thanks in advance!

Answer 1

You have a large pool.  Twin skimmers are typically installed when the surface area exceed 600sqft.  

Actually the drain is not that at all but part of the pools circulation system.  Water removed from the skimmers or surface water will cause up welling from below and a powerful circulation pattern.

Sounds like your filter needs cleaning out and or your pump and skimmer baskets are obstructing water flow. Your plumbing could be blocked too.

Instead of phenol red I would use a food coloring, blue or red work well.

The second skimmer should have a drain cover installed below it maybe several feet below water line or on the pool bottom.  You may also have split main drains on the pool bottom.  Seeing water flow on these is very difficult!

Contact a pool maintenance company.  For a service charge they could set it right for you and maybe show you how to work the equipment!

You're welcome!!

Answer 2

some pools have a device called an equalizer valve in skimmer that has a flap on bottom that you can move over hole in bottom to make the main drain work..it looks like a flying saucer a disc shaped object....or you may have a valve to turn on main drain/turn off skimmer....or a diverter valve in skimmer..depends on type of skimmer....you can check by squirting some phenol red (ph test kit solution) near main drain to see if it gets sucked in....some suction should be on main drain to get heavy debris as they sink.

Answer 3

If you push a leaf toward the main drain (use your pole & leaf net) it will suck the leaf to the drain.

Same with the surface skimmers.

Usually there is a valve to turn  them on & off.

If you have the pop up heads in the floor (infloor cleaners) the pump should just filter from the main drain.

You could let it pull 20 % from the in the wall side skimmers, if you wish.

If no infloor system, then do 50% easch way.

Try to find out who built the pool, ask them to pay set up a service call. They are best to tell you how it was designed.