i have never tried espom salt thing but you can give it a try. there is no harm in experimenting, prepare you electrolyte in start so that you dont have to wait later. buy de-ionized water and mix espom salt in it, ensure that espom salt mixes well by preheating it like quoted, put it inside batteries after draining old, attach is back with ups and let it charge and discharge for few days, later drain every thing and pour your fresh electrolyte after a light flush.
its not waist of time basically as people may differ in opinion but genius , technically sound people whom you see in life seems sound because they want to experiment in life. its not a waist of time for them. this in return creates interest in them so overall its not such a bad thing.
cell which is showing 1050-1150 is a bad cell, you can try to flush this cell for few time, try espom salt experiment on it and see if it shows an improvement later.