Proper way to measure ppm?

Just got my ppm meter… how exactly is it done? If you measure the runoff right after feeding aren’t you gonna get the ppm of what you put in?? Or do you wait a few days and test with ph’ed zero ppm water?? little confused

1 Like

Salts can concentrate in the soil/media if you do not feed enough liquid through the medium. You are looking to get the same PPM out as you are feeding.


so i do the reading the same time as feeding??Isn’t it gonna be the same as it put in? I wouldn’t think you could measure the intake so quick

@Rob10737 try this thread

SOIL, PH, PPM, RunOff / please explain 2 me


You want to water or feed until you get about 20% run off collect that and test ppm and ph
If your ppm are higher then what you put in your over feeding

How high you want your ppm will depend on what stage of growth your in


I’m just learning this myself mate I would say leave your run off for an hour or two then test the solution like you said you could be testing a weak solution but after two hours I remove the waters as it could get to wet in there

Strain; I believe Northern lights

Soil in: grow bag 5 Gal…roots organic

System type? 2X2X5 Grow tent

PH of runoff or solution in reservoir? 6.4

What is strength of nutrient mix? nectar for the gods…using half strengh


Light system, size? HGL 100 3000

Temps; 60 at night 79 during day

Humidity; 45-60%

Ventilation system; fan

AC, Humidifier, De-humidifier, NA

Co2; NA
I just did a feeding with Nectar at 6.3 PH and 474ppm before feeding… run off was 6.4 and the ppm was 980. Thoughts? the plant is 5 weeks old.


sounds to me from what @Countryboyjvd1971 said, you are over feeding. good luck on your grow @Rob10737 . the gang here will get you straightened out!

Thank you. That what it looks like… I am only using half strength but doesn’t the roots organic soil have nutes in it? I replanted using the roots organic 2 weeks ago… took out of topsoil.

i am a newbie @Rob10737 so i will let the regulars explain about that stuff :smiley:

I wouldn’t feed again till the ppm of your run off drops a bit
Are you feeding full strength as per mfg mixing guide ?
How old are your plants
@MattyBear didn’t you work with ucmjjojo usingbthe nectar line ?

1 Like

yes i’m using the nectar line at half strength… Only fed them twice. doing the feed,feed,tea,feed,feed flush regiment. Do for the tea (no nudes) on tuesday


Plant is 5 weeks

1 Like

You prob want your ppm up in the 1000 range @Rob10737 at that stage so might be time to start feeding full
I’m not all that familiar with the line I only used it one time myself and I don’t have feeding chart handy


I used it for a couple plants and then ditched the line. Too many bottles for my liking, but you’re gonna wanna feed full strength as per their schedule because they are a mostly organic line with low ppms, even at full strength :v::bear:


If you are using roots organics, I recommend pH’ing your water/nutrient solution to 5.8pH. Their website recommends this. The runoff shouldn’t be higher than 6.2.

What is the ppm of the runoff currently? In roots organics, with the flower power nutrient line I use, I water every 2-3 days to signifcant runoff (more than 20% comes out the bottom of what I put in). I use a 1/4 nutrient dosage to keep the ppm runoff at around 1000. If it dips below 1000 I slightly increase the dosage (~1/3) the next time; if it starts to run high, I just water-only the next time.

Yes I’m using roots organic with Nectar for the Gods… ph’ed at 6.3 and came out at 6.5… ppm of nite mix before feeding was 474 and came out at about 1000… I’m using 1/2 recommended dose can’t be overfeeding can I ???

1 Like

1000ppms is a good read. I find my roots organics runoff (no nutes added) when I freshly plant in it to be about 2000, so looks like your plants are working their way through the organic nutes that come in the soil.

I think getting your runoff pH more towards 6, by watering at 5.8pH, will put you in a good place.

Keep at the 1/2 dosage and adjust up or down for the next watering depending on your ppm readings.

1 Like

Good advise, thank you.

1 Like