the pro's say NO and the grow shop's say the same BUT i have done the same in a pinch, i have run out of bloom and used a general hydro mix and finished up with that. i didn't go back with what i started with i finished with what i had to use in a pinch, going back n forth on them WILL SCREW with them but if you have to use something different stay with it untill done, good luck and KEEP ON GROWIN