When I do it however the air goes directly to the filter and it does nothing to any of the returns. I lowered the water and was able to clear the side return lines however I'm stuck on the floor return in the 6' deep end. I've turned every valve and not even a bubble.
Can you please explain a little more in detail. You write that "it does nothing to any of the returns". Then you write "was able to clear the side return lines".
A few questions:
Q: How many skimmers, main drains, and returns do you have?
Q: What type of valves do you have at the equipment pad? What do they operate?
Q: Do you have a valve to close the main drain and only operate the skimmers?
Q: What are you using to push water out of the lines? Air Compressor or Shop Vac?
If you push air through the skimmer, then place multi-port on "recirculate" and air will follow the path of least resistance. Please make sure the main drain is closed while doing this. If you are having problems with air flow, then you can isolate each area. If you lowered the water a few inches below the skimmer, then clearing out the skimmers should be very easy. Plug the skimmer with a Gizmo (Teflon tape added). Then move on to the return jets and plug each one (with the black plugs). Once you are done with the return jets, then quickly open up the main drain. Allow the main drain to bubble for 45-60 seconds and then close valve to create an "air lock". Remove all the fittings on the filter and pump, etc. Place multi-port valve between Winter and another setting (no locked) to allow water to drain and to keep the multi-port valve open all winter long. Place a tie strap at the main drain so the valve is not opened accidentally during the winter.
I also add black plugs at the pump basket (Suction and Return Side) with # 10 and # 11 plugs. This is for a 2 HP Pump. The size will vary based on the HP.