IG pool closing questions

[PJM361]

What I do, is put my filter in waste position and attached my Mighty vac blower to the waste pipe which blows air in reverse direction into the pool.

I tried this but, the water geyser came out of the the 1st skimmer. So I use a gizmo then did the same on the second skimmer. Then I waited and I didn't see air bubbles in the 2 main drains or the return lines. Also tried closing off the valve going to the pump & still no air bubbles. What am I doing wrong? pump & filter are about 60" away & I'm using detachable blower from a very strong 6 HP shop vac.

[PJM361]

New problem , I used my air compressor to blow out the 4 return lines. After I capped the last one then the main drains started bubbling. It seems that my two Jandy 3 way valves are not airtight because I was still seeing bubbles with all valves closed. Also after I removed the t-cell from the return line in front of the valve I could hear air leaking back. So I'll buy a couple of 2" caps to air lock the lines.

[PJM361]

Couldn't find screw on caps that would fit so I used plugs instead. The valve going back to the returns stopped leaking but, not the other coming from the skimmer & main drains. Even with a plug in I couldn't get a perfect seal so I added duct tape on top of that plug.