I tried the coil of tube run through a refrigerator idea recently as my 75g would top 80f when its warm. I used thin 1/4" bore aluminium tube 50 feet and got a really poor flow rate, not so good but you'd expect a decent drop in temp with that but my little beer fridge just didnt have the required coldness. I gave up with that and just closed the room my aquarium is in and leave the window shaker on at 75f and turn off my heater cable.
I think to effctively use the fridge idea it would need to have an internal fan otherwise the heat transfer from water to air through metal tube is poor (air is very bad heat conductor). I did however think about using a motorbike radiator as an alternative to the tube but decided to save my money for the forthcoming electric bill.
Regards Davey Bee
Let me know if you have any success? |