well there are a couple different designs for cooling with liquids, here is a good link. not the cheapest, but it will get you started...
http://www.planetnatural.com/site/fresca-sol.html
here is another way of cooling you could make this yourself...
fig.1 is a cool tube without reflector.
fig.2 is some type of radiator (cheap heater core from a car) that is placed on either the intake air (cools light) or on the exhaust side (cools air going into room).
fig.3 is Air moving thru radiator.
fig.4 is your reservoir (a plastic 55gal drum works best and can be found cheap on craigslist) will need one per 1kw light @least.
fig.5 is the pump that circulates the liquids from the reservoir to the radiator and back.
fig.6 is cool liquid flow to radiator
fig.7 is return "heated" liquid to reservoir.
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