How to Set Up a CO2 System in a Freshwater Tank

Adding a CO2 system to a freshwater fish tank allows the home fish keeper to unlock a new world of possibilities for tank aquascaping. Not only does the addition of freshwater plants enhance the visual appeal of a tank, they can help to make the tank environment healthier by adding valuable oxygen while consuming harmful wastes and ammonia. Setting up a CO2 system may seem complicated at first, but with a few primary pieces of equipment, it can be easily established.

Things You'll Need

  • CO2 cylinder
  • Pressure regulator
  • Silicone tubing
  • Diffuser/reactor
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Instructions

    • 1

      Find a reputable and convenient location for purchasing and refilling a pressurized CO2 tank. CO2 cylinders are commonly available in 5- and 10-lb. sizes and can be either purchased new and refilled, or purchased used and swapped out when empty. Make sure the tank has recently been pressure-checked and is in good working condition.

    • 2

      Purchase a pressure regulator designed for use in aquariums or for home-alcohol production; there are single- and double-gauge versions available, but the double gauge is generally considered advisable, as you will be better able to control the exact input of CO2 bubbles, rather than just a rough pressure range.

    • 3

      Determine whether you would like to add a bubble counter, solenoid or pH regulator to your CO2 system. While these additions are not necessary (and can considerably raise the cost of the completed system), they will allow the CO2 to be shut off overnight or when the tank pH level dips too low.

    • 4

      Decide on the method of introducing CO2 into the tank: the CO2 diffuser or reactor. The primary difference is that a diffuser introduces a stream of CO2 bubbles into the tank directly, while a reactor uses some sort of pressure or pump to dissolve the bubbles before they enter the water. Reactors are more efficient, but also more costly.

    • 5

      Connect the regulator to the CO2 cylinder by screwing the regulator input valve firmly onto the tank's output.

    • 6

      Connect the regulator to the diffuser or reactor in the tank using silicone aquarium tubing.

    • 7

      Double check that the cylinder is at the correct pressure, and slowly turn the output up to around 10 psi.

    • 8

      Adjust the pressure as needed to obtain the proper CO2 rate for the plants and lighting you have selected.