Have you solved the problem yet?
I would suggest that you go to HiBlow Pumps. They are far better built and get a spare ready to operate should a problem happen. Always Always have a backup!
I would loop the airline and place the air pumps on the other side of the garage. You have placed them high due to the siphoning effect. But if all of the airlines go up first about the height of every tank then there is no need to have the pumps up so high. So move them across the room and place them on foam on the ground.
hth