It was recommended that I post this in this forum as I'd previously posted in the general one (apologies if you've seen this before.). Since all my parameters are good, they say it could be a disease issue with new fish being exposed and my existing ones are immune? Can you please read my situation and if you know how to rectify the problem so I can add new fish without them dying in a week, I'd love your input.
I need help. I have had my 55 set up for over a year and every time I get new fish (and I mean at least 30) they die within a week. I've worked with several LFS and they are dumbfounded. We've tested EVERYTHING (PH, Phos, Amonia, and all the basics plus copper, etc) and while once in a while it may have a higher Nitrate or the salinity is off, we rectify those and all of the numbers are good (I've had experts test everything and while I don't have the numbers with me, trust me when I say it looks good on paper). I have a sump, protein skimmer, etc. and a temp around 78. I set up a RODI and now make my own water (red sea salt) but I'd been using water purchased from the store so neither made a difference.
I currently have a Foxface, 3 chromis, 2 Scooters, and 2 anemones and even a few frags that have lived through everything. It's not an aggressive tank and I acclimate by floating, drip, then a "holding" cage so acclimation isn't the issue. I've tried countless clowns, tangs, angels, small toby puffers, etc. from different LFS and some will look great, swim, eat, etc. and then they just die in 5 days. I have done significant water changes in the past and I dose to keep nitrates down, etc. I need to do something different.
I don't know what to do and it pains me to kill fish (and not to mention $) Should I drain it and start over? 50% change? Please help.