If your also wanting to avoid backpressure by having the airpump inside the refrigerator, there is another solution. Keep the airpump outside of the fridge. Run lines from the pump into the fridge through holes drilled into door. This would pump air into the open space. Run lines out of additional holes drilled in the side or door that go to your air stones. You would be pushing 100% chilled air through the stones and not losing any temp by pulling chilled air through the pump. It would take a few minutes to build up the pressure inside the fridge, but should work.
Was laying out this design the other day and will be putting it together next weekend. Will throw up pics of the build as it is done.
Been there & done that,it will not work to chill a rez,it wont even lower the temp a single degree,i didnt use a fridge,i used outside air temps in michigan in the dead of winter which reach -30 below zero,i used 200 lft tubing & burried half in snow & ice & left the other half of the coil exposed to air,not one bit of cool air comes thru the lines.
The problem & why it wont work is that air pumps are piston or diofram action which creates heat,the air dont stay in the line long enough for heat to dissapate.
I use geothermal cooling for my rez's where they are underground & it works great,i tried just sinking 100 lft hose in the ground & leaving the rez above ground & that didnt work,i flood once an hour & the water in the hose didnt have enough time to cool off.
Another huge drawback to using geothermal cooling via a hose sunk in the ground is added nutrients,it adds alot more volume to the rez.
Anybody ever thought of using a drinking fountain to cool their rez?
Seems to me that a metal drinking fountian that is powered & cooled would be the exact design as a chller,build a thermostat into the power supply & you'd have a chiller.