Join Date: Jun 2007
Location: River Falls, WI
Similar experience, can't remember the product...
I had the same thing happen, probably about 10 years ago. Sure, it got rid of the algae, but wiped out a whole tank of fish. I saw the same thing you did - respiratory distress.
I tossed the product straight out. I don't remember what it was, but it was from an allegedly reputable manufacturer.