Main Drain Success Story

[bryjen]

Hi Waste im back with another question. Closed my pool today . I blew out the lines thru the skimmer closest to the pump. Everything blew out ok except i couldnt get main drain to bubble. I went out and bought a new shop vac 5hp was the highest i could find. Still couldnt get it to bubble. I had evrything plugged up and used valve to bypass the pump. Let me say I was using my pool vacuum hose since it fit perfectly into the skimmer. Is it possible that the lenghth of hose even though i had a good seal is the problem. Any help thanks.

[Poconos]

A shop vac won't have the pressure to blow a main drain. An easy way to tell how high of a column of water you can blow is to just stick the blow end of the hose into the pool and keep moving it deeper. When it stops bubbling that's the pressure in inches of water it can push. Chances are you will be lucky to get 2 feet down. You may have also noticed this but those shop vacs (the brand and the generic term) leak on the outlet side, probably intentionally, for motor cooling in case you totally block the outlet. I modified mine a little to make a better seal and get a little more pressure at the hose. As for what you do with a main drain? I know it's been discussed on this forum somewhere but I don't have one and never paid much attention to the posts.
Al