My 20g tank has been up for 1.5 months. Today I noticed my Phantom Ocellaris has a few spots of ich. I’m trying to figure out if I should dose the whole tank with Kordon ICH-Attack (allegedly reef safe) or set up a quarantine tank for the fish. I have 1 ocellaris, 1 BTA, a Banded shrimp and softies. My water parameters: Ammonia 0ppm, nitrite 0ppm, nitrate 0-5ppm, SG 1.025, PH 8.3. Thank you in advance for any response!