Did the venkatool ph meter come with three calibration packets? If so, calibrate. If not, calibration reference solution is available on Amazon. The ppm meter, in my opinion, doesn’t need calibration.
I use tap water. I think you are using distilled, which has a pH of 7 (the pH meter can’t detect this because of the absence of anything in the water) and a ppm of ~0. Add your standard calmag dose, then measure the pH and ppms. This is your baseline solution. From here, I either just pH down to 5.8 for soilless (6.5 if in soil) and add to my plants; or add my recommended dosage of nutrients, re-measure the ppms, and then pH down to 5.8 (6.5 if in soil) and then add to the plants. I jot this info down to get a feel of what kind of water I typically start with and how it ends up.
During the watering process you want to collect run-off. This means that you have to add enough water to the plant to get a significant amount of water to come out the bottom (~30% for soilless, ~10% for soil is what I have read, opinions may vary). The only danger to this is the potential to overwater the plant. If the top inch or so of those big pots are bone dry it should be ready for water. Some people will recommend only water in a circle the is the approximate width of the plant until it establishes its root system. However, this makes it impossible to get to run-off. I think you flushed last week and they handled it ok?
Anyway, when you do water to run-off, you want to collect a little in a cup and then measure the pH and the ppms. For example, I have 5 gallon fabric pots in a shower stall. I water them with about 1.5 gallons. I let it sit a minute, then I pick up a pot handle with one hand and, as the pot tilts and water runs out the bottom corner, I collect that in a cup with my other hand.
If you are in soil, you want that pH to be between 6.3 and 6.8. If you are, your putting your plant roots in a position to succeed.
Second, you want your ppms of the run-off to be less than a 1000 for seedling and early veg plants, and over a 1000 for late veg and flower. Late flowering can be as high as 2000+ when the plant is eating up for the buds. Anything over 2500 is putting your plant at risk of nutrient burn or other issues caused when your soil is “loaded”. Anything under 250ppms, especially when the plant is established, is going to make her hungry and potentially nutrient deficient. Somewhere on this site there is a scale of what is ideal for the stages of the plant.
Let me know if you have any questions.
