Main Drain Blow Out On Older Anthony Sylvan Pool

[mallethead@verizon.net]

Hello,

We moved into a home 3 years ago with a gunite Anthony & Sylvan pool that we are told is about 30 years old. I prefer to close the pool myself but I am perplexed about one aspect of blowing out the lines. I've already done everything including balancing chemicals, covering the pool, detaching the filter motor, moving the filter and motor to the shed, etc.

The part I am not confident about is the main drain. The skimmer has two round holes - 1 inlet and 1 outlet. They are located on the sides of the skimmer and not on the bottom as I've seen in many youtube videos.

We have a main drain in the deep end, a drain in the "jacuzzi" section (more like a little walled off bench), 2 returns to the main pool, and 2 returns to the jacuzzi.

In the skimmer there is:

1. water coming into the skimmer from the skimming action

2. water going out the lower hole to the filter/pump

3. water coming IN the other hole

It's the 3rd part that I don't understand. Water flows IN through this hole non-stop. The filter is off and removed. The water level is dropped 16 inches. The water level appears to be below the level of this inlet hole in the skimmer but the water keeps coming.

I'm assuming there is a law of physics at work here but it seems to me that if the hole in the skimmer is above the water in the pool it should stop pushing the water through.

I used an air compressor hooked up to the filter pump to blow out the rest of the lines and filter.

In the end, I believe that I need the Mighty Vac to put it into this non-stop hole and blow until I see the bubbles come out of the main drain and then quickly push in the rubber stopper before the water rushes back up the line. There is no valve between the main drain and this inlet hole in the skimmer.

Sorry for the long post but thanks for any suggestions.

Jerry