ICH infected fish with smoothhound shark

[alteredego]

I've lost all recent introduced fish due to ICH.
Maybe someone with tons of knowlege on a healthy tank can come to take look and see what I'm doing wrong to get these fish all stressed out. I'm running a 600+g tank with plenty of flow for a FO. the sump is a 125 with about 150lbs LR and good size block of bio slab, and a ton of bio balls in the filter pad area. A 1hp chiller to keep the water at a good 76-79 range.
I do a 55g water change every sunday, and all tests prove good.
I run two good sized skimmers all the time and pull out all kinds of junk.
Yesterday i had to resort to a product called kick-ick a very high priced chem. which to perform a complete 15 day treatment it will cost me well over $300.00 when i really should have found the source of the stress. I also feed kinda heavy do to the eels and shark, and i do include garlic, which i have never seen work.
help needed.

[Flobex]

well if they are recently introduced, it could have been stress from moving to your tank... how long has the tank been running/ parameters?

[alteredego]

they were put in on friday. the tank is about 3months old but 110g and all LR, bio-slab were re-used from the other tank. I waited until all spikes
went down. the other fish are great, shark, lunar wrase, foxface, trigger, eels, damesels, scopas tang.
parameters look like: ammonia=0, nitrite=0, nitrate=.10-.20, ph=8.4

[alteredego]

they were put in on friday. the tank is about 3months old but 110g and all LR, bio-slab were re-used from the other tank. I waited until all spikes
went down. the other fish are great, shark, lunar wrase, foxface, trigger, eels, damesels, scopas tang.
parameters look like: ammonia=0, nitrite=0, nitrate=.10-.20, ph=8.4