How to lower the PH in fish tanks

Updated April 17, 2017

PH is the measurement scale used to quantify the acidic and alkaline levels in a solution based on a scale of 0 to 14 with 7 being neutral, a ccording to The Tropical Tank website. If the pH in your fish dips down below 7, it means your water is too acidic, but if the water reaches above 7, the alkalinity is excessive. You have to keep the pH level of your tank at the correct level to keep your fish healthy so if the pH goes too high you will have to lower it as soon as possible.

Fill a bucket with water from your tap and add an air stone. Leave the bucket exposed to the air for 1 to 2 days to allow the pH level to regulate.

Use the water from the bucket to change 10 per cent of the tank water. So if you have a 5 gallon tank, replace ½ gallon of the water. Do this once a week to bring down the pH level.

Replace the substrate (the material on your tank bottom) with peat moss. As the water flows through the tank and the substrate, the peat moss can significantly lower the pH.

Install a carbon dioxide filter onto your tank to increase the carbon dioxide in the water. Raising the carbon dioxide neutralises the alkalinity in the water.

Add driftwood decorations onto the bed of the tank to lower the pH. Start off with fewer pieces of driftwood and increase the amount if necessary.

Pour chemical pH reducer into the tank water to quickly lower the pH. This method is only advised if you have an extremely high proficiency with chemistry and manipulating pH levels.


Choose the fish you raise based on the natural level of pH in your local water to avoid having to control the levels yourself.


Do not follow any pH level adjustments without constantly checking the progress or you may overadjust and possibly kill your fish.

Things You'll Need

  • Bucket
  • Tap water
  • Air stone
  • Peat moss
  • Carbon dioxide filter
  • Driftwood tank decorations
  • Chemical pH reducer
Cite this Article A tool to create a citation to reference this article Cite this Article

About the Author

Based in Princeton, N.J., Jim Stewart has been writing travel- and business-related articles since 1987. His work has appeared in “Inc.” and “Business 2.0” magazines and online at Wired. Stewart received the John Goldenberg Award in 2007. He holds a Bachelor of Arts in English from The Ohio State University in Ohio.