You got it, You'd think having Pristine conditions would be ideal but it isn't for what ever reason, Having that much water should absorb any abnormalities but it doesn't, Why it happens i'll never know. Countless Reefers have set up systems only to see losses in live stock, or Mega SPS loss. I've been around awhile and setting up any system initially can be boring as hell, Sure it's a beautiful tank, lots of potential and it will be a great system no doubt about it. It Will, but it's gonna take time. You said the Coral were fine, great. Nows the time to just sit back and enjoy those 3 fish, go slow. The most successful system I ever had was set-up and just sit with Rock and sand circulating for 3 months, It was hard but there it sat getting all my perameters stable, getting the Phosphate down to near nothing, then slowly, clean up Crew, One fish, wait a month, ad another, wait again, pretty boring but I never lost a fish or had algea issue, Really nice system, you'll be fine just takes time.