Had my tank tested last year for parasites, no ich. Did have uronema, so I broke it down and sterilized it (not just because of that, need to fix plumbing and some other things). So I agree that ich does NOT exist in all tanks.Having done both methods, I find QT to be pretty remarkable and I am not a believer that Ich exists in all tanks just waiting for a suppressed immune system. It's a pathogen with a definitive life cycle that can be broken via strict QT and copper.