You get clean ice by making it yourself. An easy way is to sanitize an ice cream bucket, and fill it with your water (either boiled tap water, if you boil your water, or bottled water) and putting it in the freezer with the sanitized lid. You can make a couple of those, if you need too, or do a smaller bowl also, depending on how much ice you'll need to cool it.
I used to cool my wort in an ice bath in the sink until it was under 80 degrees (about 20 minutes) and then put it into the fermenter with cool tap water. It got it to 65 degrees very quickly without overcooling.
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