Aluminum

I gold plate stuff myself, so I can only think in terms of cost... a flashing would be about $5, even a thick plating would cost < $100.

Cheaper than a chiller... a little bit.

 

could you gold plate the inside completely?

 

DIY chillers have been covered again and again on this forum and others. At the risk of sounding like a nay-sayer and poo-pooing everyones ideas, my friends, the ideas are not new. There are at least half a dozen threads--quality threads on 3Reef--where the folks tried this, and reported their results over time. As far as I read, not a single DIYer cleared the hurdle.

The roll of tubing inside the college mini-fridge won't do the trick for 2 reasons: first, there's not enough heat transfer between the plastic tubing and the inside of the fridge. And--if there was a way to do it, with say, a 100' coiled up length of very high quality stainless steel or gold electroplated piping, the condenser in these mini-fridges are simply not made for 24/7 load. The fridge would burn out in no time, heating your room to unbearable levels in the short life beforehand.

If it were that easy, fellas, we'd all be DIYing chillers. I'm afraid the category of chilling your aquarium water, realistically; will have to accomplished by a proper chiller.

If you have the need, save up the money and buy a quality name brand unit that's of ample capacity for your system.

I might just have to do this sooner than later, unfortunately; as I just upgraded my Coralife Aqualight Pro from a dual 150W to dual 250W halide fixture.

And one last thought--if you buy a chiller, do not put it in your stand next to your sump, as it will create a pretty hot ambient. And you thought skimmate smelled bad at room temperature.

 

Ya, even if you did do it, I don't think your gonna get enough heat exchange out of that unit. You'll get more by just blowing a fan over the top of the tank.