I am looking to buy all 3 of these meters and would like to know all the required maintenence for them. It seems for the PH meter I need PH 4 and 7, cleaning, solution, and storage solution. I also see ph 10 solution, do I need that? If I regularly calibrate it and keep it in the storage solution how often do I have to use the cleaning solution? Do the other meters need cleaning or storage solution or should I just rinse it in water/leave it in water? What do I do in the case I have a 2 in 1 meter? What about a 3 in 1? Thanks