Watering twice a day is not advised. As IR says, "Cannabis requires wet/dry cycles" Let the soil dry out first, maybe until you see the plant wilt a little, and then give it a good watering with a little run-off. If your soil is well aerated with perlite and you have drainage holes, it's hard to over-water with that method.

The meters can be good, or they can be off. I just pick up the pots and you can tell that way if they are dry or not.