[Karren H]

The air locks on hand pumps are very poor and will leak pressure off.  I use an air valve in the air line between the domes and the pump.   Open it and pump then shut it.  If your air lines are tight and leak free  the pressure will be maintained all night.  You can get the air valves at a pet supple store in the fish department.   They cost like a couple dollars.  Make sure they will fit your air hose tightly.  I place mine between the tee connector and the hand pump and actually remove the hand pump after I shut the valve.   By the way, you can use your mouth to draw suction and really do not need a pump.