Hi all

I'm thinking of a DIY chiller for my saltwater aquarium. The current commercial chillers are far too expensive and inefficient for the same compressor HP rating. Here's some pics of the aquarium chiller I'm using



The box on the left is the titanium heat exchanger ... its so small because of the high cost of titanium. This chiller is rated at 0.5HP



I think the actual compressor rating is abt 1/4HP. My idea is if I build a chiller with a similar compressor but oversize the titanium exchanger and change the aluminium evaporator fins to copper fins, would that make the chiller more efficient?

What are the possible negative effects of oversizing?
Why would someone use aluminium for the evaporator fins when copper is a much better heat conductor?
What are the things to look out for?

Thanks alot!