UV wont work, trust me. I did 60 watts of UV on a 55g tank, with 50gph flow.. which was low enough to turn the tank over and kill ich. Didnt work. i eventually gave up and just kept damsels and chromis in that tank as those fish never catch ich
I tried meds like malachite green, herbal crap, and even cupramine.. cupramine just killed fish that never got ich and caused other issues.
I HIGHELY HIGHELY HIGHELY, recomend you get a 20 long from petco.. Put some live rock and little bit of sand from your main tank in it, if they have a coral on it, pry the coral off.. your corals are tiny anyway so itll be fine. Catch your fish and put them in hyposalinity 1.007-1.009 for minimum of 4-6 weeks. Youll notice after 3-7 days the ich will fall off and never show up again. Trust me man. Raise your salinity in the 20g after 4-6 weeks, but leave the main tank empty for 8 weeks at least to starve the parasites.
This is the only real way to get rid of ich without hurting your fish with cupramine. Hyposalinity wont work if you have wrasse, anthias, butterfly fish, or flame angels. Everything else seems to handle it just fine, i did hypo for 2-3 months on some tangs and fish and they did just fine.
This is coming from a guy who lost 600+ in fish from ich in a 135g and 55g and 30g tank. Before i wised up and bit the bullet and did hyposalinity. What i did though was i took my corals put them in the 20 long, and did hyposalinity in my 135 gallon tank. But thats because i had more tangs and fish then you do and a 20g would be too small for them all.
But i mean if you wanna lose a 200-300$ achillies tang, and a $100 yellow tang by taking the risk of a uv and other crap medication to manage ich go for it.. I cannot stress enough the only way to stop this is to eradicate it.
You have two real options.. do cupramine in a QT tank and leave the main tank empty for 2 months. Or do hyposalinity, take the corals out put them ina small tank or take the fish out.
I know this sucks, trust me i didnt want to do it either. i was like god darnit.. i have to wait for months before my beautiful tank is back to normal.. but yea i got tired of losing fish..
I had a yellow tang.. on his death bed.. same size as yours.. i mean riddledddddd with ich.. i tested hypo on him in a 5g tank "5g is all i had man and its enough for a few weeks temp" in 3-7 days ich fell off, never came back. He had ich for 3 weeks prior.. and stopped eating.. he got to skin and bones thats how much weight he lost. Hes still alive 2 months later thanks to hyposalinity, and i can feed him every 5 minutes and he eats like crazy.