Adjusting the pH of your hydroponic system requires modifying the water's chemistry after nutrients have been added. To protect your plants from chemical shock, always adjust in small, incremental steps.
1. Choose Your Adjusting Solution
Always use commercial, highly stable hydroponic solutions. Be careful when handling pH adjusting solutions as they can be very corrosive. Always read and follow the manufacturer's directions for dosage and safety.
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To Lower pH (If above 6.5): Use "pH Down" (typically phosphoric acid).
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To Raise pH (If below 5.5): Use "pH Up" (typically potassium hydroxide).
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What to avoid: Do not use household vinegar, lemon juice, or baking soda. They break down rapidly, causing massive, unstable pH swings within 24 hours.
2. Dilute the Solution First
Concentrated acids and bases will burn bare plant roots if poured directly into the system.
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Scoop a small cup of water out of your main reservoir.
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Add 2 to 3 drops of your pH adjuster directly into the cup.
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Stir the cup thoroughly to dilute the chemicals safely.
3. Add to the Reservoir and Mix
Incorporate the diluted mixture back into your main system.
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Pour the contents of the cup directly into your main nutrient reservoir.
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Let your water pump or air stone run for 10 to 15 minutes to circulate the mixture completely throughout the tank.
4. Re-Test the Water
Verify that the adjustments brought your levels into the ideal range.
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Take a new reading using your digital pen, liquid test kit, or paper strips.
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Aim for the baseline sweet spot of 5.8 (anywhere between 5.5 and 6.5 is acceptable).
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If the pH is still out of range, repeat the process with another small, diluted dose.