Cannabis and H2O: The Real Deal on PPM and EC

Yo, what’s good my fellow cannabis growers? It’s ya boy Dan here to break down some knowledge on water quality for your grows. Water is essential to your plants, and understanding its quality can take you from a novice to a pro. In our last blog, we talked about pH and why it matters. Today, we’re going in-depth with PPM and EC.

First off, let’s talk PPM – this measures the amount of nutrients present in your grow medium. Understanding PPM is vital because it guides your next feed and helps you avoid over or underfeeding your plants. You can measure PPM using most TDS meters.

EC, on the other hand, is electrical conductivity, another measurement that helps us determine nutrient levels in our growing medium. The higher the nutrient levels, the higher the EC reading of your runoff. Measuring EC is simple with our DiST 4 Pocket Conductivity Tester by Hanna Instruments.

To get a clear picture of how much nutrients your plants are getting, you need to measure the PPM or EC of both your nutrient solution/reservoir (if you’re using hydroponics) and your runoff. Ideally, the PPM or EC reading of your runoff should always be lower as it shows your plants are taking up nutrients when you feed them.

If there’s no change in PPM or EC between your nutrients and runoff, this means your plants aren’t taking up nutrients correctly. This is usually caused by spikes or drops in pH. If the PPM/EC reading is higher in your runoff than in your nutrient solution, you’ll likely be dealing with salt buildup around the roots – use an enzymatic line cleaner to clean your plant roots.

Knowing your PPM helps you avoid possible burning by letting you know when to adjust the amount of nutrient minerals you add to your water. Cannabis enjoys 500-600 ppm after cloning, 800-900 ppm when vegetating, and 1000-1100 ppm when flowering.

There are many probes, devices, and meters on the market that can measure PPM. The most common is a TDS meter (total dissolved solids). What you go for really depends on your budget and desire to get technical with your grow.

EC or Electrical Conductivity measures the salinity of a water sample. Saline water conducts electricity better than pure or reverse osmosis water because more ions are dissolved in it. If your water is too saline, it can affect your plants by increasing the toxicity of singular ions at the root ball and increase osmotic pressure at the roots inhibiting nutrient uptake.

Organic soil and outdoor growers have an advantage again with ppm and EC. The microorganisms provide a buffer that helps protect the plant from fluctuations in ppm or EC, and there is a greater margin for error when watering.

But don’t be complacent! Always check your water quality even from rivers and creeks before using it for your plants. Rainwater may be neutral but carbon dioxide dissolves in it making it into a weak carbonic acid with a pH of about 5.6. And when you put your water through a reverse osmosis filter, it makes your water completely mineral-free so never use it unmodified to flush your plants or as a foliage spray.

So there you have it fam! Understanding water quality for cannabis growing may seem technical but actively working to ensure you have the best water quality will minimize any potential growing problems as well as give your cannabis what it needs to thrive. Stay lit!