diy poor mans chiller

pic and link to DIY thread, tell me what you guys think over at the DIY section

-basically the box on top is the tank, the black lines are connectors
-the box below is a closed lid styro box
-the tubing inside the styro box will probably be copper ? (will it leech metals?)
-the box inside the tank is a internal filter

http/www.fishforums.net/index.php?act=ST&f=16&t=95988

Im not very good with technical stuff, but how high is the tank temp normally in your tank? There are many cheap alternatives to lowering tank temp...