Don't be too dishearted yet, it is all part and parcel of the hobby which we all learn from mistake from one another .
My advise to you is after doing a major water change, let everything stabilise for few month without adding any new livestock, you will find your tank getting better and better back.
Stock fish as slow as possible, especially for Angel and butterfly fishes which are prone to ich and diseases. Getting established and healthly fish from reefer will avoid time and money going thru QT process.
Hope it helps.
Sent from Singapore Reef Club mobile app