The only reason for using a digital meter is because the tint of the nutrient solution throws off the color test and then your not sure of anything.

For first timers don't buy exspensive and things need to be checked for calibration weekly. To check without using calbratio solution just keep checking your base water it should never change. My R/O water is 7.0 never changes so I can tell if my meter is off.

pH METER (Hand Held) Milwaukee pH600

Some of the best deals are not in the hydrostore.