Which PH value and which EC value in hydroponics / aeroponics?

Hydroponics and the pH / EC value – key to success

In the world of hydroponics, the pH value and the EC value of the nutrient solution play a crucial role. If you want to achieve high yields, you have to keep a close eye on these values. In this article, you will learn everything you need to know about the pH value and the EC value in hydroponics and how to set them optimally.

What is the pH value?

The pH value is a measure of the acidic or basic effect of a solution and is expressed on a scale of 0 to 14. Values ​​below 7 mean that the solution is acidic, while values ​​above 7 indicate a basic solution. A pH value of 7 is considered neutral. The term "pH" stands for "pondus Hydrogenii" and refers to the weight of hydrogen.

The importance of pH in hydroponics

The pH value influences the availability of nutrients for the plants. Depending on the pH value, certain nutrients are more or less accessible to the plant. In hydroponics, the aim is to achieve an optimal pH value that maximizes nutrient availability. If this is not the case, deficiency symptoms or toxic effects can occur. For example, many plants develop a magnesium and calcium deficiency at a pH value below 5, while a pH value above 6.5 can lead to iron deficiency. The correct pH value therefore determines the nutrient availability for your plants. pH values ​​can fluctuate - e.g. due to algae, which consume carbon dioxide during the day - so the pH value will rise and fall again at night. Dead plant remains are decomposed and release acid accordingly. Tap water influences the pH value through carbonate, rainwater has an acidic effect. If you use rock wool for cultivation, it should be rinsed well several times beforehand, as it will already have a higher pH value of around 7-9. This is also something to keep in mind when you then use this rock wool in your system.

Optimal pH values ​​in hydroponics

For most plants, the optimal pH in hydroponics is between 5.5 and 6.5. This is the range where most nutrients are most readily available. However, there are exceptions: blueberries prefer a pH of 4.5 to 5.5, while lavender and mint prefer pH values ​​of 6.0 to 7.0. Pumpkins are less demanding and thrive at a pH of 5.5 to 7.5. Conclusion: pH values ​​of 5.5 to 6.5 are therefore optimal for most plants.

Measuring the pH value

The pH value of a nutrient solution is measured with a pH meter that works electrochemically. The electrical potential of the glass electrode depends on the hydrogen ion concentration. The measurement accuracy is maintained through regular calibration with special solutions (pH 4, 7 and 10). Alternatively, acid-base indicators can be used, but these are less accurate.

Adjusting the pH value

Medium to strong acids are used to lower the pH value. Suitable acids are pH-Down, nitric acid, phosphoric acid and citric acid. For beginners, pH-Down is recommended, a ready-made pH reducer with a buffer effect.

Strong bases such as pH-Up, potassium hydroxide and potassium carbonate are used to increase the pH value. Again, pH-Up is particularly useful if too much pH-Up has been added.

Automatic pH control

Modern hydroponic systems use pump-based fertilization computers to automatically measure and adjust pH. These systems use pH probes and dose acids or bases as needed to maintain the desired pH.

Fluctuations in pH value

The pH value of a nutrient solution can be influenced by temperature, substrate, nutrients, plants, rain, algae and microorganisms. Fluctuations often indicate insufficient buffering properties of the nutrient solution. A pH buffer can remedy this and stabilize the pH value.

Tips for measuring and stabilizing pH

• Measure the pH about one hour after adding fertilizers.
• Always check the pH at the same time of day.
• The optimal water temperature for measurement is 22-24 °C.
• Store the pH probe moist and calibrate it regularly.
• Use a high-quality pH meter and protect the glass probe from shocks.
• Attention: mix and dissolve agents for separating and increasing the pH value first in water

Using tap water in hydroponics

The carbonate content of tap water can affect the pH. If the hydrogen carbonate content is above 75 ppm, the pH will rise. This can be reduced with pH down or by reverse osmosis. It is important to test the water quality and, if necessary, use water filters to remove contaminants and ensure plant health.

What is the EC value?

The EC value (electrical conductivity) measures the concentration of dissolved salts in the nutrient solution and provides information about the amount of available nutrients. A higher EC value means a higher nutrient concentration. The unit of the EC value is Siemens per meter (S/m), although millisiemens per centimeter (mS/cm) is usually used in hydroponics.

The importance of the EC value in hydroponics

The EC value is an indicator of the nutrient concentration in the solution. An EC value that is too low indicates an insufficient nutrient supply, which can lead to growth problems and deficiency symptoms. An EC value that is too high, on the other hand, can lead to salt stress, which damages the plants and inhibits their growth.

Optimal EC values ​​in hydroponics

The optimal EC value varies depending on the plant species and growth phase. The following guidelines generally apply:

• Seedlings and seedlings: 0.5 to 1.0 mS/cm
• Vegetative phase: 1.0 to 1.5 mS/cm
• Flowering and fruiting phase: 1.5 to 2.5 mS/cm

Some plants, such as tomatoes, can tolerate higher EC values ​​of up to 3.0 mS/cm, while more sensitive plants such as lettuce prefer low EC values.

Measuring the EC value

An EC meter is used to measure the EC value. This device measures the electrical conductivity of the nutrient solution, which is proportional to the concentration of dissolved salts. Regular measurements are important to ensure that the plants always receive the right amount of nutrients.

Adjustment of the EC value

To increase the EC value, add more nutrients to the nutrient solution. To lower the EC value, dilute the solution with pure water. When adjusting the EC value, proceed gradually and measure regularly to avoid overdosing.

Fluctuations in the EC value

Fluctuations in EC can be caused by water loss, evaporation, uptake of nutrients by plants, and replenishment of nutrient solution. It is important to regularly monitor EC and adjust accordingly to ensure consistent conditions for plant growth.

Tips for measuring and stabilizing the EC value

• Measure the EC value regularly, ideally daily.
• Keep the probe clean and calibrate it regularly.
• Make sure the nutrient solution is well mixed before measuring the EC value.
• Use high-quality fertilizers specifically designed for hydroponics.

You can find the devices we have extensively tested and which are suitable for the EC value and pH value under accessories in our shop.

Conclusion

Both the pH and EC values ​​are key factors in hydroponics and have a significant impact on the availability and uptake of nutrients by plants. By regularly measuring and adjusting these values, deficiency symptoms can be avoided and optimal growth conditions can be created. With the right tools and techniques, pH and EC values ​​can be effectively controlled and the yield in hydroponic systems can be maximized.