How to vac to waste, not lose prime?

[9753]

When I vac to waste, when the water level drops below the skimmer, I lose pump prime and can no longer vac. How can I keep keep vac'ing in that situation?
Seems that main drain doesn't suck at all. I noticed skimmer had one of the two holes plugged and I've been unable to unscrew that plug (hopefully not cemented shut). If that likely connects to main drain, wouldn't that allow me to continue vac'ing by pulling water from drain and keeping prime?
I've been vac'ing some to filter with help from wife who must hold the vac tube only partially over vac plate in skimmer to keep prime, but the finer particles get spat back via returns.

 

[HermanTX]

Welcome to TFP.
Usually the port nearest the pool is the line that connects to the main drain if the plumbing is set up that way.
Can you take a photo of the plumbing that is leading to your main filter pump so we can see how many suction lines you have?
Also, do you have 1 skimmer or 2?

Also, the of a vacuum plate makes it easy to connect the hose however, have you tried to put the hose only directly into the port in the skimmer? Fill the hose full of water and hold your hand over the end and quickly place it in the hole. Most hoses have diameter that should go into that port. It is not foolproof so it can pop out if not seated good.

 

[1poolman1]

When I vac to waste, when the water level drops below the skimmer, I lose pump prime and can no longer vac. How can I keep keep vac'ing in that situation?
Seems that main drain doesn't suck at all. I noticed skimmer had one of the two holes plugged and I've been unable to unscrew that plug (hopefully not cemented shut). If that likely connects to main drain, wouldn't that allow me to continue vac'ing by pulling water from drain and keeping prime?
I've been vac'ing some to filter with help from wife who must hold the vac tube only partially over vac plate in skimmer to keep prime, but the finer particles get spat back via returns.

Why are you removing so much water that the level goes below the skimmer? You would probably be better off with an automatic cleaner of some type rather than losing that much water.

 

[9753]

Can't seem to remove it. Got enough leverage with a crowbar+socket wrench setup, but the inside edges of the plastic started to give way before turning as you can see on the photo.
Anyone know of an attachment made to remove these plugs?

 

[Darin]

When you start getting low in the skimmer throw your water hose in there so that it will keep the skim to hose adapter "covered" somewhat. It will buy you a couple of inches.

 

[9753]

Found a decent solution just as Darin noted--had the water hose flowing straight into the skimmer while vacuuming, and that seemed to work best, didn't lose prime.
Do wish the main drain was actually open, but the previous owners probably closed it off and used only their robot.
Need to get this Aquabot Industrial Z3 fixed...
So many things to do, so little time.