Nutrients, pH, and Maximizing Efficiency

Did you know if your pH levels climb too high or fall too low, some nutrients become available to your plants at toxic levels while others become completely unavailable? Ranging from 0 (acid) to 14 (base), the pH scale is used to determine the acidity or alkalinity of a substance. Plants growing in hydroponics solutions which are either too acidic or too basic have trouble absorbing what they need for steady growth. A pH of 7 is considered neutral, and, for optimal nutrient uptake, the pH of your nutrient solution should be between 5.5 and 6.8 depending on the types of plants you'll be growing.

Handheld pH meter

Because evaporation, temperature, and amount of light can affect pH levels, frequent monitoring of nutrient solution pH is critical. If you aren't using a pH monitor that remains directly in the nutrient bath to offer continuous readings, you'll need to measure the pH of your nutrient solution at least twice a week with a hand-held pH meter.

Hand-held meters feature delicate glass probe tips which are dipped into nutrient solution for periodic testing, and they offer easy-to-read digital results right away.

If you find that your solution is too acidic or too alkaline, you can make incremental changes in pH with PH Up or pH Down liquids as needed. Some solutions commonly used to lower pH include nitric acid, phosphoric acid, citric acid, and vinegar. Potassium hydroxide is typically used to raise pH.

Finally, to prevent possible problems, take a pH reading of the water you will be using and adjust it as needed before mixing your nutrient solution, and never use hot water when mixing hydroponics nutrient. (The 'scale' that you see on the inside of hot water pipes is a form of calcium that will raise your pH to irritating levels which cannot easily be reduced.) Aside from staying on top of the pH levels in your hydroponics system, you should also test the strength of your nutrient solution because, as the water in the solution evaporates, the nutrients become more concentrated.

Also, as the plants take in what they need, the nutrient concentration can, in turn, weaken. Since hydroponic nutrients are mainly made up of salts, and salts in solution conduct electricity, you can measure the concentration of your nutrient solution by measuring how well it conducts electricity. Hydroponic gardeners all over the world monitor nutrient levels this way-but they have different preferences for the format of their test results.

PPM meter

Growers in the U.S. often examine a simple ratio known as parts per million (PPM). High concentrations of salts increase the solution's electrical conductivity (EC) and this is the standard measure used in Canada, Europe, and elsewhere. A test of electrical conductivity can help growers to determine when it's time to add nutrients. Like pH testers, EC meters are available in less expensive, hand-held models and more expensive, continuous-read varieties, too.