Does PPM/EC matter for healthy cannabis growth?

[wannabeagrower]

I wanted to talk about PPM/EC meters and whether they are important for cannabis growers.

So PPM stands for "parts per million" and measures how much "stuff" is in the water. EC stands for Electrical Conductivity and essentially measures the same thing by putting an electric current through the water, and is influenced by dissolved ions including nutrients. They measure the same thing essentially, they give different numbers. PPMs will be like 200 PPM but EC will be like 0.4 EC. A single PPM meter typically actually measures the EC and converts to PPM for you.

So a grower will make nutrient water, then measure the total levels. Higher numbers means there's a lot of minerals and other things, and it's unknown if those are nutrients or something else. Low numbers is closer to "pure" water.

Some growers have tap water that naturally is relatively pure, but some growers have tap water that's very "hard" and has lots of PPMs. But that doesn't tell you much about what's in the water, and whether it's good for plants.

Anyways, I've heard there are different schools of thought when it comes to PPM/EC and weed. On Reddit, it seems like everyone believes that measuring and controlling PPM/EC is key to getting good fast and healthy plant growth. In fact, they even say that you don't need to worry about PH, only PPM/EC! Yet I've noticed, somehow all their plants look unhealthy. And so many Reddit posts are essentially, "I stopped measuring PH and started measuring EC and now my plants look bad."

So I feel pretty confident PH is more important than PPM/EC.

But if the PH is correct, how much does PPM/EC matter?

The other school of thought seems to be to just follow a nutrient schedule, and then adjust the strength based on plant appearance. So if it's pale all over then give more nutrients. If it's dark green and getting burnt tips, pull back. And other than that just pay attention to PH. But other things can affect leaf color like PH, bugs, watering problems, heat, etc.... So maybe PPM/EC is better when you're struggling to figure out why all your leaves are turning yellow.

What's the better approach? What are the pros and cons of measuring PPM/EC vs just looking at the plants and adjusting nutrient levels based on that? Who measures both PH and EC?

 

[Orggrwr]

From what I understand ppm/ec is important in coco because it's an inert medium with no nutrients at all. So the plant gets all nutrients from watering and ec is a way to make sure the plant has what it needs, when it needs it. In soil, especially living soil and super soil, it's much less important because the nutes are mostly coming from the soil itself. Since you can't know exactly what's in the soil without a soil test the ec of any nutrient water is irrelevant, as you would just be guessing how much is left in the soil. I grow in my own living soil so rarely give nutrients with water. I have an Apera ph/ec meter from when I dabbled in coco years ago but all I use it for nowadays is to check my well water from time to time. Having to constantly measure ph/ec is one of the things that steered me away from coco.

 

[golfnrl]

I measure PH and EC but not VPD. You have a good understanding of the terms and how they are applied. What's your opinion? The vast majority of plant problems are caused by improper PH at the roots. PH simply cannot be ignored IMHO unless the grow medium is super soil where the dirt moderates the PH. Growing in coco would/will be a disaster unless the PH is correct. What's the better approach? It depends on the grower and the preferred grow method. My guess is some experienced growers can look at their plants and make adjustments off of that. I prefer to measure everything, watch the plants and make adjustments from there. I grow in coco so I have to know what and how much my plants are getting. I feel like EC is important to know how strong the nutrient solution is just to protect the plants from the nutrient manufacturers. Otherwise, why is the advice always to start the nutrient dose at 1/4 to 1/2 strength?

 

[Chipmunk]

KISS

 

[Allotrope1000]

Yes! Go @Chipmunk! KISS.

My set up: 50/50 c/p, 7 gallon fabric pots in greenhouse. GH Fora Trio + CaliMagic. Autoflowers.
I:
- measure nute pH, not EC or VPD.
- use half the bottle's recommended strength. Back off if see beginning of nute burn on leaf tips.
- water daily to slight runoff.
- monitor plants for bugs, abnormal colors, and react appropriately.

If I have four plants and want to increase yields 25%, I simply add another plant.

What don't I do? Agonize about It.
Read the tutorials and subscribe to the newsletter. Simple works. Got ounces of extra bud by not worrying about it.

 

[Chipmunk]

Well said Allotrope!!

 

[Chipmunk]

I would add this with Allotropes list if your a tent grower. Keep your average RH @50% and your tent temp at @80 deg. That helps have a happy plant!