Yes my tank was crowded. I got hit with velvet. I thought it was ich at 1st because I could count the spots. Then a day later it was to late they where covered in the dust that everyone talks about. I lost 23 fish. I had copper on hand and formalin. I treated them when I 1st saw spots and it didn't matter. It wiped them out. I think my mistake was I was ramping the copper up slowly like I do all my fish and should have done it all at once. I did a formalin bath for 45 min 1st then copper.Keep it going, this is the way to reef. As said above, any % increase in success due to this method is WAY better for a new reefer than quick starting things. I don’t get it, don’t rush it, eventually your tank will be so crowded you’d wish it would have been slower.