How to Naturally Raise Alkaline pH Levels in a Fish Tank

Aquarium fish require specific levels of acidity or alkalinity to survive. This may not be available right out of the tap. Levels of acidity and alkalinity are measured on a pH scale, which goes from one to 14. A pH of seven is neutral, while a pH below that is described as acidic and above that is described as basic or alkaline. One problem with attempts to alter pH levels is that some water holds a pH level better than others, which is a property known as buffering or KH. This situation requires some experimentation. A freshwater aquarium should have a pH of between 6.8 and 7.8. Marine aquariums range from 7.8 and 8.3

Things You'll Need

  • pH testing strips
  • KH testing strips
  • crushed coral
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Instructions

    • 1

      Test the pH. Use the pH testing strips according to the manufacturer's directions. Test every few days and record the data to give you a good idea of your water's buffering capacity. If you are doing water changes or adding water, test and record the tap water or distilled water before you add it to your aquarium.

    • 2

      Test the KH. KH testing strips allow you to test your aquarium water's buffering capacity. This may not be necessary if your pH is relatively stable.

    • 3

      Remove dead plant matter. If you grow plants in your aquarium or use driftwood, be aware that decaying plant material tends to lower pH in your water and decrease its ability to buffer. If you have a low pH or low ability to buffer, look for this.

    • 4

      Add crushed coral. Crushed coral increases pH and increases buffering. Baking soda also raises pH, but even a small amount can cause a big swing, which doesn't change buffering. Be aware that adjustments to your aquarium's pH should be done gradually. A rise of .3 on the pH scale in one day can kill your fish. Add small amounts and test the effects. With crushed coral, you may need a 1-inch layer on the bottom of the tank.