ok, so I am very new to this new and exciting hobby and want to learn as much as I can to enjoy the beautiful marine life. That being said I feel like I am the fish Death Reaper.

I have a 55 gal viewing tank and a 20 gal coral tank and a 10 gal quarantine tank. ( that one was converted from freshwater)

The 55 is doing very well, we have 2 black clowns, a diamond goby a flame hawk 2 chromies and a tomini tang. they are doing great. The coral tank is fantastic, I have so many different beautiful corals in there and they are thriving..... I guess that brings me to the quarantine tank huh?

Well that one isn't so good. we use that tank for when we get fish via mail or when we buy new fish from the local store or when one of our little fishies are sick and need some one on one treatment.

Current Dilemma

We purchased 2 fish from online and received them this week. a gorgeous Coral beauty and a little turd my husband picked out (bicolored blenny). We have researched that the Kent Garlic helps stimulate a healthy appetite and debatably helps with ICH. We have been treating the tank with the garlic and with Herbtana. ( we do this because we have learned that its best to treat them before introducing them to the main tank so everyone doesn't get sick.)

Well the coral beauty died tonight. My question is does anyone dose their tank with these 2 and successfully acclimate their fish? we turned off the protein skimmer, the only filtration the tank has right now is biofiltration. Is that what is killing them? Are you only supposed to dose with one?
PLEASE HELP!!!!
I don't want to keep killing fish!!