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