How to Adjust the PH Level in a Hydroponic Garden

How to Adjust the PH Level in a Hydroponic Garden. Balancing the pH levels in your hydroponic garden is essential to the healthy growth of your plants. A plant needs to stay at its proper pH level in order to absorb nutrients. Each plant has its own optimal pH level, but most plants like a pH between 6.0 and 6.5, which is slightly acidic. Daily testing and adjustment of your hydroponic garden's pH levels will pay off in beautiful, healthy plants.

Things Needed

  • pH testing device: paper test strip, liquid test kit or digital meter
  • Phosphoric acid
  • Nitric, sulfuric or citric acid (optional)
  • Potassium hydroxide
  • Step 1

    Add any nutrients/fertilizer that you normally use before testing or adjusting the pH in your hydroponic garden. Nutrients will affect the pH levels, usually raising them as the plants use the nutrients.

    Step 2

    Check the pH level using a paper test strip, a liquid pH test kit or a digital pH meter. If you're using a paper test strip or a liquid test kit, compare the color of the dye to the color chart to determine the pH level.

    Step 3

    Add phosphoric acid to lower the pH if your levels are too high. You can also use nitric or sulfuric acid to lower pH, but these are more dangerous chemicals. Citric acid is commonly used in organic hydroponic gardening to lower pH.

    Step 4

    Add potassium hydroxide to raise the pH level. You can usually find potassium hydroxide that is already diluted commercially.

    Step 5

    Check the pH again using your test kit, paper strip or digital meter. Add more potassium hydroxide or phosphoric acid until the pH level is where you'd like it to be. You should check the pH level in your hydroponic garden daily.


  • The liquid pH test kits are slightly more expensive than the paper test strips, but their results are easier to read. The pH meters are even pricier, but they are quick in delivering results and the most accurate.


  • Avoid skin contact with the phosphoric acid, potassium hydroxide or any other chemicals you're using to adjust the pH. These chemicals can cause burns and are especially dangerous if you get them in your eyes.


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