Homemade CO2 injection using Gelatin

Created on 29 Oct, 2018
Revision of 14 Nov, 2019

This is one more option to the traditional recipe of CO2 generation and injection in planted aquarium. The gelatin method described here is dimensioned to work for roughly a month. After reading this article, if there is any doubt, please engage in the comment section bellow in order to get more details.

First part: Gelatin

Materials Required:

  • 1 PET bottle of 2L (Coca-Cola, Sprite, 7Up, Mineral Water, ...) well washed.
  • 4 packets of common gelatin (any flavor).
  • 1 cup of sugar, ±200gr.
  • 1 teaspoon of baking soda.


  1. Prepare the gelatin according to the package instructions and, while still warm, add the cup of sugar and teaspoon of baking soda to dissolve.
  2. Put the mixture in the bottle and leave it in the refrigerator until the gelatin hardens. Do not use all the space available in the bottle. Leave enough space in the top area in order to add the second part of the recipe.
  3. Once the gelatin has harden, remove it from the refrigerator and leave it at room temperature.

Second part: Fermentation

Materials Required:

  • 1 teaspoon of dehydrated organic yeast (sachet).
  • 1 teaspoon of baking soda.
  • 1 cup of sugar.
  • 1L of warm water.


  1. Dissolve the organic yeast and baking soda in a small amount of warm water. Put it inside the bottle and watch the level. There should be a free space at the top in order to contain the foam that will form, about 7cm is great.
  2. Complete the bottle with warm water and screw the cap. The production starts in no time.


  • Warm means really warm. If it is hot instead, the yeast will be killed and goodbye recipe.
  • This mixture generates foam. Therefore you should never fill the bottle completely, otherwise there is a risk of such mixture getting into the aquarium.

Budget Issues

Colorless gelatin sold in sheets is much more expensive than ready-made gelatin, for example:

  • 1 sheet of colorless gelatin = $3.90
  • 4 boxes of ready-made gelatin = $2.60

Besides, colorless gelatin also requires more sugar while the ready-one has already half the sugar needed.

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