Before moving to a plate chiller, I ran two 50' copper coils - one in the wort and one in a big bucket of ice and water. I'd hook up the garden hose and start with just water in that big bucket, and run the hose until temps got below 100 F, then I'd add bags of ice to the bucket and take it the rest of the way down. I've gotten the wort down to 58 F in less than 15 minutes in July here in Georgia with the ground water measuring in the upper 70's to the low 80's. For a 5-gallon batch, I could blow through two 20 Lb bags of ice on the hottest of days but heck; it worked!