Used my DIY immersion chiller today. It was made from 50' 3/8" Soft Copper tubing wrapped around a 5 gallon corny. Not the prettiest looking thing but it did cool 5 gallons of boiling wort to 65 degrees in just over 10 min.
Now you just need a pump and a whirlpool aparatus and you can cool that baby super fast.
Nice. I was thinking about that, I have one of those big party tubs and I was thinking I could fill it with ice water and use it as a pre-chiller or something like that.
What many of us do (At least in the summertime): Is use tap water to about 120°-100° and then pump ice water through it from that point.