Hi yosun, so far, I've been using the drops that come with a GH ph kit, but when they run out I'll get a digital ph pen.
As for the water, I was using tap, but this last grow I decided to start using RO from one of those machines around town, It's really cheap and reasonable for small grows as far as toting around the big jugs. I will be getting an RO filter in a few weeks, because my grow tunnel is going to need 15 gallons per watering. Filling 6 5 gallon jugs twice a week might arouse some suspicion.
As for the water, I was using tap, but this last grow I decided to start using RO from one of those machines around town, It's really cheap and reasonable for small grows as far as toting around the big jugs. I will be getting an RO filter in a few weeks, because my grow tunnel is going to need 15 gallons per watering. Filling 6 5 gallon jugs twice a week might arouse some suspicion.