When using an EC meter, do I test my plain ph adjusted tap water first, it measures 0.6 EC, and subtract that from the EC of the diluted nutrient solution? Also trying to figure out the FoxFarm soil feeding schedule, you can get that here. It lists a week 4 EC range of 2.1-2.3, up from the previous week, but calls for adding less nutrient. How does the EC go up if no extra nutrient? If you mix a gallon of growbig and it has EC of say 1.8 and then you add some bigbloom to it wont that raise the EC? So do I measure each nutrient seperately? I have a BluLab truncheon.
First - You should not be using source water with an EC of .6 Second - Yes you need to subtract your original EC from your final EC to get you actual EC of the nute solution.