I need some experts advise ive had so many fish loss in quarantine…. For example in my 55 gallons quarantine im using copper power normally at 2.3 ppm checked always with hanna checker … tank is cycled correctly ammonia is at 0.0 and nitrite at 0.0 ppm … lets say i put a couple of fish in today even with copper starting at 2.0 ppm then ramping up … fish dye specifically at night every single one when i wake up every single fish is dead .. really good oxygen to in the water wave maker on top and air pumps in water actually two air stones … i cant get it keep loosing money and its just becoming a nightmare Can someone please help of what it might be or what needs to be done … during the day ph is around 7.9

they use to be in other tanks but i heard supposedly that matrix wont hold copper or leech out ?