Manual pH meters are not easy to use. There are a lot of things to do with the annual ones while the digital pH meters just need to be dipped into the samples and BOOM you the result on the small digital screen showing you the exact pH value of the sample. We recommend you going for the digital pH meters as they are more accurate and easy to use. If you are serious with your hydroponic growing, you need to go for more accuracy and towards more ease. This also helps you if you are a beginner and have never used the pH meters before.