I have a 1/4 hp Polar.
I only have a 20gl rez.
After I insulated my rez,
the chiller was much more efficient.
I am going to move the rez and the chiller
into their own space
to further isolate them from the heat.
The chiller puts out heat like an airconditioner.
I am going to move my chiller,
and then build a wall
to channel the heat away from the rez,
which I am also going to isolate from the grow room,
to make everything more energy efficient.
I think you could buy a cheap window unit
and duct it into your rez,
and that would lower the temp
just by blowing cold air
over the surface of your nute solution.
I can get used 5000btu window units
for $50-75 in my neighborhood,
I'm sure you can find the same.
Check the yellow pages under "appliance, used"
Just don't use any copper tubing in your rez,
cause the nutes will react.
The really nice thing about the chiller
is the thermostat,
which keeps the nutes
within 1.5º of your setting.
But I wouldn't worry about getting too cold,
some hydro farmers in Canada,
are running solution temps as low as 50ºf,
without chillers.
(wouldn't that be a bitch)
.