Looks like Ich. I use Garlic-Xtra from Kent. I know its not medication but it works for me, Although its not fool proof. I dose my tank for 3-4 days with the Garlic or longer if it dosen't go away. I also dose my tanks weekly with Garlic. There are other ways and medications. but this works good for me and you don't have to add carbon afterwards and wont hurt Inverts or corals. Im sure others will post with ways that work for them read them and decide which sounds good for you and try that. Good Luck. PS I also have a UV
sterilizer running with a slow flow to help wipe out parasites.