at first i used regular green car antifreeze but noticed that it just didn't get cold enough. my lil refrigerator/freezer really don't get that cold. the freezer part prolly doesn't get to even 40* so i just use straight water and don't worry about it freezing. i usually keep the beer i'm about to drink in the freezer part and it never freezes. just gets it to "drinking" temp. if any coolant is used, i would only suggest about a teaspoon of antifreeze to 3 liters of water. i don't think you'll need to worry about it being toxic or not because it's not going to come in contact with anything you drink.
water cooling setups for pc's would be perfect, especially if you allready have them.
if your fridge gets to 40* i think you'll be fine. you may want to put a bunch of ice in the coolant container just to get it started, but once you initially cool the box to the right temp, the insulation should keep it relatively close to that desired temp and you won't have to put ice in it anymore. my lil fridge is kindof on it's last legs as far as cooling goes. but it does enough to keep this system cool and keeps my box at a steady 70 degrees. just keep the box closed. as soon as u open it, it will loose the chill. my father in law controls the AC in this house and it's rarely under 80.
yeau some foam insulation around the tubing would prolly be a good idea. for one to keep the water from warming up during travel, and for another to keep the condensation from dripping on the floor.
some of that coolant for computers i think is pretty good stuff if i remember correctly. that may be worth looking into for my setup. i think it gets colder than freezing with out freezing, but with little effort... gave me a good idea whiskey
and this whole idea with putting the pump in my freezer may not be a bad idea for cooling my pc. i also have a water cooled setup for my computer.
