Best pH for Hydroponics (How to Monitor and Adjust)

Having the best pH for hydroponics keeps every plant in its best growing conditions. Along my hydroponic journey, I realized that even with the right temperature, lighting, and nutrients, my veggies and herbs still suffered if my hydroponic pH level isn’t optimum.

The ideal pH for hydroponics is 6.0, but 5.5 to 6.8 is still acceptable. It is recommended to monitor the nutrient solution pH every 2-3 days. If it is higher or lower than the optimum, one can use pH up and pH down adjusters. Vinegar can be used to lower the pH and baking soda to make it higher.

I am sure most of you have already heard of pH. But in this article, you will be taught how to monitor and adjust the pH based on your plants’ needs. Practicing this knowledge made my hydroponic garden more productive. I hope that after reading this, the same will go for you!

Ideal pH for Hydroponic Plants

In general, 5.4-7.0 is the best pH range for leafy vegetables, 5.8-6.5 for fruiting vegetables, and 5.5-7.0 for herbs.

Before we move further, let us have a recall. The potential of hydrogen, prominently known as pH, is a measure of acidity or alkalinity. Now you may ask, why is it important in hydroponic gardening?

This concept is relevant because different levels of acidity affect the availability of nutrients. Thus, as a hydroponic gardener, you need to find the right pH level at which all of the nutrients are available.

The pH level is measured on a scale ranging from 0 to 14. The 0 value indicates that the solution is too acidic, while 14 indicates the most basic. Of course, we also have the mid-value, 7.0, telling us a pH-neutral solution—just like water!

Effect of pH on Nutrient Availability

The pH of a hydroponic solution dictates the availability of nutrients for the plants. For instance, nitrogen, phosphorus, calcium, and magnesium are less available if the pH of the solution is acidic. Whereas, iron is more available in acidic conditions.

Plants only absorb and use hydroponic nutrients from your nutrient water if the pH is within the range the plants can use.

Generally, extreme low and high pH decrease nutrient availability. Low pH also lowers the availability of macronutrients and secondary nutrients such as nitrogen, phosphorus, potassium, sulfur, magnesium, and calcium. Conversely, a high pH decreases availability of micronutrients like iron, manganese, copper, and zinc.

In a too acidic hydroponic solution, nitrogen might be less available. To recall, nitrogen is one of the most essential elements that affect leaf development. Thus, if it is less available to the plant, it may lead to stunted growth and yellowing of leaves.

Measuring and Monitoring Hydroponic Solution pH

It is advisable to measure hydroponic solution pH every 2-3 days using commercially-available pH meters.

Well, the first step is to have a digital pH meter. It does not have to be a costly one and you can easily get it from online shops! Here’s one of the pH meters available on Amazon.

The next step is to calibrate your pH meter. For this step, you need to purchase buffer solutions to help you have a correct pH reading. Here’s one that you can find on Amazon.

4 Easy Steps to Calibrate pH Meters

1. Clean your pH meter. You can use distilled water and then wipe it off using a paper towel.
2. Dip your pH meter into the pH 7.0 buffer. If your pH meter reads 7, accept the value. If not, you can adjust the reading on your pH meter. Rinse and dry your pH meter after doing this.
3. Dip your pH meter into the pH 4.0 buffer. Similar to step 2, accept the value if the pH meter reads 4.0. If not, adjust the reading on the pH meter. Again, rinse and dry.
4. Try to measure other solutions. You can start with water, which will also return a value close to 7. After that, rinse, dry, and, finally, measure your hydroponic solution.

When measuring the pH of your hydroponic solution, dip the pH meter into the nutrient water for about 2 minutes. After that, the value that will be displayed is your pH reading.

But what if it is too low? Or too high for your veggies and herbs? Do not worry, we can adjust that!

How to Adjust pH of Your Hydroponic Solution

Commercially available pH up and pH down products can adjust the pH of hydroponic solutions. However, household materials such as vinegar, lemon juice, or baking soda can also be used.

Commercially Available pH Control Products

To maintain the right pH levels, commercially made “pH up” and “pH down” products are available on Amazon. Below is my personal recommendation for pH control kits.

To use this, you need to measure the pH of your hydroponic solution first.

When the pH of Your Hydroponic System is Too High

For instance, you are growing strawberries and your current pH level is at 8.0. This means your nutrient solution is too basic.

If you will go back to the pH figure above, strawberries are best in pH of 5.5 to 6.2. Thus, you need to lower your pH and use the pH down solution.

When the pH of Your Hydroponic System is Too Low

On the other hand, if your nutrient is too acidic at 4.0 pH, you will need a pH up to get to the right level.

But did you know that you can also use food ingredients readily available in your home to maintain the right pH?

Household Materials to Adjust pH

Vinegar and lemon can be used to lower the pH of a hydroponic system, while baking soda can raise the pH level.

It definitely works! But, there is a downside. They are weaker compared to the commercially available pH adjusters. Thus, you need to adjust the pH more frequently.

How Often Should I Check pH in Hydroponics?

It is recommended to measure hydroponic solution pH every 2-3 days and maintain the recommended range depending on the plant.

The pH varies because of certain factors like temperature and nutrient concentration. The nutrient solution evaporates. When this happens, the solution becomes more concentrated. As a result, pH levels fluctuate a lot.

This fact makes pH monitoring, not a one-time task but rather a regular one!

FAQs

Should I check pH before or after adding the nutrients?

Always check the pH after adding the nutrients. This is because nutrients can lower or raise the pH of your hydroponic solution. For instance, nitrate-based nutrients usually lower the pH of a solution.  

Can you lower pH by adding water?

Water can either lower or raise a hydroponic solution’s pH. For instance, if your pH is too acidic, you can add distilled water to raise the pH, making it closer to 7.0. On the other hand, adding distilled water in a basic hydroponic solution will lower the pH. 

How do you keep a stable pH in hydroponics?

It is important to control your external conditions, specifically, temperature. When it is too hot, the hydroponic solution tends to evaporate excessively—leading to a nutrient concentrated solution. Moreover, strictly using products (nutrients, pH adjusters) designed for hydroponics is advised since they are already tested by their manufacturers.

Are pH, EC, and TDS the same?

They are not the same. The pH value tells the acidity and basicity of a solution. On the other hand, EC (electric conductivity) indicates nutrient concentration in the hydroponic solution, whereas TDS (total dissolved solids) is a measure of other molecules in water different from hydrogen and oxygen molecules.   

What is the best EC for a nutrient solution?

Generally, the best EC (electric conductivity) range for hydroponic crops is between 1.5 and 2.5 mS/cm. EC is an indication if your veggies and herbs are getting enough nutrients. Veggies such as lettuce and other greens, need a considerably lower EC than fruiting crops, like tomatoes.

Summary of Best pH for Hydroponics

For plants to survive, they need specific growing conditions, and pH is one of them. In general, the ideal pH for hydroponics is 6.0, but 5.5 to 6.8 is still acceptable.

It is relevant to monitor pH because external factors like temperature affect nutrient concentration. Measuring pH every 2-3 days is a good practice for hydroponic gardeners. To do this, a pH meter can be used.

Furthermore, to adjust the pH, one can use commercially-available pH up and pH down products. However, food ingredients such as vinegar and baking soda can also be used.

Sources

• “Describe How Soil pH Affects the Availability of Each Nutrient” by Northeast Region Certified Crop Adviser in Cornell University
• “pH Meter Calibration/Use Instructions” by California State University, Stanislaus