most people dont even do that when adding ro, if the tank is stable and the water conditions are prestine, you wont drop or raise your ph levels to critical levels, you will only see fluctuation of PH throughout the day due to the hydrogen ions that are positively charged ,they alter the charge environment of other molecules in solution....meaning the higher hydrogen ion concentration in your water the lower your PH goes...this fluctuates throughtout the day and you will have ph swings , nothing to worry about, since every week when you do a water change the PH buffers in our salt will replenish the water and stablize the ionic molecules of H2O(water).... but to me its always good to check your PH periodically throught the day and then let it go to the next day test PH again see if it is too low then something with your elements in the water must be replenished....best way to do this is use a 24hr digital PH readout....ya know what i mean!!!!lol...i read alot....sry...lol