How to Make the PH Go Up in Aquaponics

An aquaponics system is a combination of aquaculture and hydroponics --- it uses the same water supply to sustain both aquatic animals and a plant garden. Since animals and plants differ in their preferred pH levels, an aquaponics system is typically kept at a narrow pH range between 6.8 and 7.2 to serve as a compromise that is beneficial to both. The pH of a system gradually decreases over time due to chemical processes caused by beneficial bacteria and the system's biofilter, and so the pH of the system will need to be manually increased every so often.

Water testing kit
Calcium hydroxide (hydrated lime)
Potassium hydroxide (caustic potash)
Bucket
Safety goggles
Rubber gloves

Instructions

- 1
  Use a water testing kit to check the pH of the system; you only need to increase the pH if it is below 6.8.
- 2
  Add a very small amount of calcium hydroxide (hydrated lime) to a bucket of water and mix it thoroughly. Pour the contents of the bucket gradually into the system throughout the course of a whole day. Mix the bucket before each application.
- 3
  Check the pH 12 hours later to determine the pH change. Use slightly less calcium hydroxide in the next batch if the pH rose by more than 0.2 from the treatment. Use slightly more calcium hydroxide in the next batch if the pH rose by less than 0.2. Use the same amount if the pH rose by approximately 0.2.
- 4
  Repeat the calcium hydroxide treatment each day --- adjusting the amount as necessary between applications --- until the pH of the system is between 6.8 and 7.2.
- 5
  Continue testing the system's pH daily. The next time that the system drops below 6.8, replace the use of calcium hydroxide with potassium hydroxide (also known as caustic potash). Use the same dilution method used for calcium hydroxide. Continue alternating between the two chemicals for subsequent treatments.

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