How do you measure ppm?

Obviously I need a ppm meter. (which I just received in the mail) but I often see people measuring their nutrients in ppm. But how exactly do you get that number? Im feeding in late flower and after adding my bloom and my calmag, my ppm's measured at about 650.

My water straight from the tap measures somewhere between 100-150ppm. So is this 650 my tap ppm + bloom + calmag?

Is that how most people measure it? Just take the ppm's after everything is added? Doesnt that make the results pretty different from person to person? Someone elses tap water could be 250-300ppm, and a lot of people add more than just calmag plus A or B. Im just trying to get a feel for how im going to measure out nutrients when I start hydro in the fall.

LOL yup can get confusing. I just use the final number after everything and that's my EC. I really don't pay much attention to the recommended levels and keep things lower then watch the level over a week, if it goes down I add a bit more next time and visa versa.

I use Peters. EC fertilizer only. Ph all. Water starts at .4. I run around 1 EC so I add Peters until it reads 1.4. Add my calmag if needed and then pH the mess.

Budley Doright said:

LOL yup can get confusing. I just use the final number after everything and that's my EC. I really don't pay much attention to the recommended levels and keep things lower then watch the level over a week, if it goes down I add a bit more next time and visa versa.

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So if your at a good level of nutrients the ppm shouldn't go down too much? But if you don't have enough nutrients the ppm will go down because their absorbing all they can? am i getting that right?

papa canna said:

So if your at a good level of nutrients the ppm shouldn't go down too much? But if you don't have enough nutrients the ppm will go down because their absorbing all they can? am i getting that right?

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Pretty much. I think technically it isn't because they are absorbing all they can, it's because they are taking up more Nutes than water vs more water than Nutes. What you're aiming for is the rate to be equal. In a perfect environment your ppm would never change as the plants used the water. This is super hard to actually pull off. Some growers tend to go heavy on one side or the other. I go low. And use the total ppm after adding Nutes as my ppm. My tap comes out around 150-250. And I run my hydro/ aero at 550-650 ppm. So 350-500ish ppm of Nutes in addition to whatever is already in my tap.

^^^^What kmog said and it's true that it's hard to find the spot but if it's minor changes your good

I never got an equilibrium, can never hit that sweet spot. I'm one month into flowering and at 650ppm max (RO water)