Last year when we built our pool, the PB added two lines to the main drains which both go back to the equipment pad. One line is plumbed to the side outlets of each drain and goes to the pump then filter. The other line is plumbed to the bottom outlets of each drain, also goes to the equipment pad, but is just left as a pipe sticking straight up with not even a cap. Where this open line attaches to the drains, those outlets are closed with screw in plugs (I believe - I will confirm with goggles as the water warms up). He did this as a safety factor in case one of the lines was damaged during construction as a backup.
I am interested in using this extra line to top off my pool by sticking the hose into it when needed since my water source is also at the pad. Can I just open up the outlets in the drains and use it this way? I don't see why not because the suction at the drain shouldn't try to pull from that pipe when sufficient water is always available via the pool filled with water. This will allow me to keep from having a hose running across the deck during fill times.
I tried running the hose into it last year and it just overflowed. So that is what leads me to believe its closed with plugs in the drains. It can't really be blown out the way it is (plugged), so the pool closer just poured antifreeze in it. If I remove the plugs, it should then be able to be blown out and plugged from the top as well.
I appreciate any confirmations or otherwise.
As an aside, I suppose the way to work under water is to just attach a hose to our cheap snorkel set and have someone hold it above water (or set a brick on in it to keep it out of the pool)? Haven't had a need to work underwater before (ever).