Cost about 75 dollars to make which is cheaper then a fan and I also run this to my res so not I by does it water cool my lights but cools my res temp
I am not here to Bash you ,I agree this can be done ,but not for 75.00 , even you said you filled it with Antifreeze , witch at best is $10 per gallon and you are taking a big risk using something that can Kill in small amounts
if failure occurs ,even the smallest amount of seepage.????
I would look in to using something else like sodium chloride ( cheeper also) but you will have pump failures unless you upgrade to a pump with Brass inners.
the other thing I would do is strip a thermostat out of a window AC unit , wire it in series with your pump attach the sensing bulb on the return line .this will give you pump on and off cycles to adjust your tempeteture .giving you a much more advanced system then what you have now.