Do you also overwater or underwater your plants all the time? Then this is the solution to ALL your problems ;-)
This aqua meter is made specifically to measure the pH value in your soil, rather than how moist or dry your soil is. Color change tells you the right time to water. Just stick it in the soil and leave it in the pot. No batteries needed.
When the aqua meter is white, you should water your plant, when it's blue, there's still enough water in the soil and you don't need to water your plant.
You can replace the refill every 6-9 months for ideal efficacy.