Hydroponic Growing Terms

Andrew Hobbs

October 21, 2021
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pH, ppm, EC; what does it all mean?

If you are learning to grow, you’ve probably come across these terms already. By now, you’ve probably read about ideal pH ranges and measuring your ppm. Or, should you measure your EC. Wait, what do those terms mean again?

Each of these factors are important, especially for hydroponic home growing. And, it can all seem a little intimidating. The following is a quick glossary of terms to make it easier for you to get started with your first plant.


Hydroponic growing is a style of growing that uses no soil. Instead, the plants roots are placed in a water and nutrient solution. The roots then use the nutrients from the solution, rather than using nutrients provided by soil and/or fertilizer.



pH is a scale of acidity (or basicity) in a liquid solution. It is one of the most important factors in hydroponic growing. If the solution is too acidic (pH too low), or too basic (pH too high), the plant will not be able to uptake nutrients properly. For this reason, it is important to maintain the pH balance of the nutrient solution within the ideal range for your plant.

The best way to measure and monitor pH is by using an electronic pH meter pen. Alternatively, a chemical kit will also provide good results.

The nutrients provided in the Mary Grow Kit will have some pH buffers included to ensure that pH balance is easy to maintain. Once you mix the nutrients with water, measure the pH balance with a pH pen or chemical kit. If the pH is too high, or too low, you can adjust the balance by adding the appropriate pH control solution. It is a good idea to re-measure the pH balance after 24hrs and the Mary control app will remind you to do this.

pH Down, is an acidic solution that lowers the pH level. pH Up, is a basic solution that raises pH level.


Parts Per Million, or PPM, is a measure of the dissolved nutrients in your solution. Think of this as the strength of your nutrient solution. You might see this also measured as TDS, or Total Dissolved Solids. Essentially, this measure is used to determine how much nutrient has been added to the water.


Electrical conductivity, or EC is also used to measure the strength of the nutrient solution. Unlike the PPM measurement, an EC meter will determine strength by measuring the ability of the solution to conduct electricity. While it may seem counterintuitive, measuring the EC is the most accurate way to determine the strength of, or concentration of nutrients in your solution.

Too much, or too little dissolved nutrient can cause growth problems or even kill your plant. If you are using the Mary Grow kit, each nutrient pack is pre-measured to make sure the correct concentration is achieved. That way, you don’t have to worry about EC, PPM, TDS, or anything besides your pH level. Once you have a few grow cycles under your belt, if you wish to start experimenting with your own nutrients, we recommend getting yourself an EC meter.


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