I need to treat my 220 gallon tank for ick.....I always seem to get a spot here and there every few months, but the residents dont seem to be bothered nor does it get bad, just a spot here and there.....tank conditions are fine, and I usually keep coppersafe in there. Other tankmates are silver dollars and a large Jardini Arowana...... I would like to knock this out once and for all, and I have been told that Metro will do the trick......next time I think I will buy a UV.....any thoughts or concerns about Metro?