How to Reduce the Alkalinity of Aquarium Water

Acids in driftwood reduce alkaline levels in aquarium water.
i Driftwood image by Bailey from

Humic acid and tannic acid in driftwood, bogwood and peat moss are a fish-keeper's best friend when it comes to reducing alkalinity in an aquarium. There's no need to use harsh pH adjusting chemicals when mother nature can safely do the job for you.

Step 1

Check the aquarium water with a pH test kit. Litmus paper kits are the easiest type to use; grab a strip, dip it in the aquarium water, wait a few seconds and compare the color against the chart on the box. Test tube and reagent kits are a little more complicated, but don't be put off by the thought of scary science lab equipment. Simply take a water sample, drop the required amount of reagent into the test tube, give it a shake and check the color reaction on the chart.

Step 2

Find two or three pieces of driftwood or bogwood or buy a couple of chunks from a pet store if you're not sure what you're looking for. The size will depend on the size of your aquarium and how much you need to reduce the alkalinity. Reclaimed wood from a beach or forest often contains parasites or diseases, so boil it first to take care of any bugs and unwanted visitors lurking in the logs.

Step 3

Place one piece of wood in the bottom of the tank, then sit back and wait for the wood's natural humic acid and tannic acid to work their magic on your aquarium water. Test the water every couple of days to check the alkalinity is going down. If you don’t see results after a week, add another one or two pieces of wood and continue testing until the water reaches the required alkalinity.

Step 4

Get creative and make a peat moss bag if your aquarium still needs an extra boost to bring down the alkalinity. Squeeze a handful of moss together and wrap it loosely in a square of muslin cloth, tying the top with string until it looks like a neat little bag. Drop the moss bag into the aquarium or hide it away inside the filter if you don't want it on display. Continue monitoring pH levels once or twice a week.

the nest