ph control help?

so im a little confused on how to control the ph of my growing...i was thinking that it went like this: get a ph meter and measure the ph of the soil itself then get a ph control kit to make sure that the water u r feeding the plant is the correct ph and adjust accordingly????

You need to test the water you are giving the plant and then what the pH is of the runoff water. You then adjust the water you are feeding it accordingly

i have found the easiest way to control it is flushing and using RO/distilled water..