Also to Completly Depressurize an Tiny Airlock i need 6 Huge Tanks that are Completly Empty which Really Sucks, and Putting that Air inside the rest of my Spaceship doesnt work since the Pumps arent strong enough.

I am using 2 Impeller Pumps that have each an Medium Motor

Thank you for report but it's not really clear why you cannot. You can use regular pumps to pump air into custom or premade tanks. Deepening on the pump power you should be able to compress it to certain level.