A 30 gallon at a minimum. I'm assuming large means 6" or larger? What type of angel, and damsel?
Can you give a size in inches?
I placed all the fish from my 125 in a 30 for a hypo treatment. That was 2 True percula clownfish (2.5" & 1.5") a Sailfin tang (5"), a Foxface Lo (5"), bicolor blenny (2.5"), coral beauty angel (3.5"), etc.
Be sure to add some PVC
pieces (T, 45 elbow, 90's) of varying sizes that can be used as hiding/resting places.
Ich Attack is probably not worth the money. Hyposalinity or a copper based medication are the only sure cures I know of.