FAQ: Is it possible to overdose Seachem Reef Fusion 2™?

It certainly is. An overdose of Reef Fusion 2™ can result in a sudden and stressful shift in pH and KH.  If pH or KH of the water is still incorrect despite repeated additions of a buffer like Reef Fusion 2™, it is likely that there is a high concentration of acids or buffers in the aquarium that are resisting the change in pH.  It is also possible that magnesium levels are so low or calcium levels are so high that the calcium is precipitating your buffers out as soon as you add them.