From a fellow grower What should the ppm and ec be for cannabis plant in the sixth week of flowering, I am a beginner grower I have a plant in hydroponic I have seven in soil. First of all is the PPM the same as EC? I checked run off on my plant and soil which by the way is 5 to 6 weeks into flowering, the PPM showed 327 and the cm (?) was 698!!
1 Like
Multiply the EC reading by 1,000 and divide by 2 which gives you PPM in the NACL scale. For PPM to EC, multiply PPM by 2 and divide by 1,000. (Your ‘698’ is more likely ‘6.98’)
You are getting good data but your PPM/EC is way low. I would want to be around 1,000 ppm at that point in flower.
Man this is how I do it seedling 200 to 250 almost in veg stage 200 to 400 in veg stage 400 to 600 late veg. 600 to 800 early flower 800 to 900 middle flower 900 to 1000 late flower 1000 to as hi as 1500 just keep an eye on them they let you know what they like.
First, what are you using for your nutrient program?
Next, what strain(s) are you growing? Bloom week 6 of a sativa has verrrrrryyyyyy different requirements than Bloom week 6 of an indica and they both have different requirements than bloom week 6 of a hybrid - so we should start there.
The way PPM/EC works is like this: PPM is a measurement of the total amount of dissolved solids in a solution. In our industry that generally refers to the dissolved salts in our nute mix.
EC measures the electrical conductivity of all dissolved solids in a solution - like, the actual element from the periodic table. Since all elements have some capacity to conduct electricity, an EC reading is incredibly specific and accurate.
An average PPM meter measures the EC reading of your solution and then converts it to a PPM measurement. Because of that conversion, the average PPM meter is technically less accurate than an EC meter. That level of accuracy is generally unnecessary for the average grower. EC measurements are most applicable in the laboratory setting.
This is where it gets weird and confusing: PPM meters are calibrated to measure PPM differently from country to country so the accuracy of your PPM meter actually depends on its country of origin. (Seriously - it’s ridiculous). So, considering the fact that PPM meters are already performing a conversion, the fact that they’re converted differently in US meters than say, meters manufactured in Russia or something. (US ppm meters use a.50 conversion rate while meters from elsewhere can convert around .70 - that’s a pretty big difference)
EC is a more universally understood reading of how much of whatever is dissolved in a given solution.
With that being said, there’s no need to measure BOTH ppm and EC. If you’ve already got a good EC meter (like, a legit one) then by all means, go with it, but for the most part, home growers don’t require that level of accuracy; a decent ppm meter will provide the necessary accuracy for a successful home grow.
I hope that helps and it wasn’t too confusing. I have a tendency to babble. :-)