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BIO-CO2

Overview

• Basics
• Building the reactor
• How to dissolve the CO2 in the water
• Starting the reaction and maintainance
• Resources

 

Basics

The biological CO2-production is based on three ingredients:

• Water
• Sugar
• Yeast (vacuum dried)

The yeast fungus will consume the sugar and produce CO2 and alcohol. While the CO2 results as a gas, a mix of water, alcohol and unprocessed sugar remains.

 

Building the reactor

The reactor size must match the size of your aquarium. You can use the following to build a reactor by yourself:

• Plastic bottles for Beverages (No glass bottles! See warning.)
• Food Containers made of plastic (!)
• Canisters of all kind made of plastic (!)

IMPORTANT: No Glass! Never use glass containers for the reactor!

The container (now reactor) must be hermetically sealed. Drill a small hole (6mm) in the cover of the reactor and use hot glue to fix a connecting piece for the air hose to it. The collar of the connecting piece must be inside of the cover. Use enough glue so everything is air tight.

Here some photos of a canister for distilled water that is being turned into a CO2-reactor:

Reccomended sizes of the reactor for your tank:

• Tanks up to 100L: 1.5-2L reactor size
• Tanks up to 200L: 5L reactor size
• Tanks up to 300L: 10L reactor size (2 x 5 L)
• Tanks up to 500L: 10-20L reactor size

The size of the reactor is not related to the amount of CO2 that is produced per minute, but there is another relation:

The larger the reactor is, the less often it has to be refilled in order to produce the same amount of CO2 per minute.

But larger reactors are also more difficult to refill. Canisters of more than 5L are not reccomended. Better use more than one canister!

Here now our reactor with the glued-in connection piece:

How to glue it together:

1. First drill the hole (6mm)
2. Remove leftovers from the drilling and degrease everything with alcohol or spirit
3. Degrease the connecting piece as well
4. Apply hot glue on the collar of the connecting piece and press it in the hole from inside (not like here shown in the photos from outside!)
5. Wait until the hot glue is cold
6. Cover the inner and outer side of the connecting piece with enough hot glue so that it will be sealed.
7. Wait for the hot glue to become cold... DONE!

That's it. Use normal PVC or Silicone hose or, even better, Dennerle CO2-proof hose to connect the reactor to the CO2 outlet. More about how to get the CO2 into the water, see below.

Here a few photos of other reactors:

Simple 1.5L reactor from a Pepsi bottle, the gas dissolves into the inlet of the Tunze filter.

 

Dual reactor with two 5L canisters supplying CO2 into the filter inlet of a 250L aquarium .

 

6L reactor for a 112L aquarium.

 

How to get the CO2 into the water?

You cannot use the same devices as with CO2 from the pressure bottle. You can use:

• Flipper
• CO2-Snail
• Filter inlet

Flipper and CO2-Snail you can buy at the pet shop. Other devices like micro-CO2-dissolvers or devices you use normally for oxygen supply to the aquarium cannot be used because they will cause high pressure in the system:

WARNING: Never block or regulate the flow of BIO-CO2 with a valve or something similar. ! DANGER OF EXPLOSION ! Parts of exploding reactots can cause serious injuries if you do not follow this advice.

Apart from that BIO-CO2 is cheap and safe.

Flipper:

 

Starting and maintainance

Ingredients for the reactor filling for a 5L reactort:

• 4L water (NO WATER FROM THE AQUARIUM!!! Only fresh chlorine free tap water or filtered water)
• 1kg sugar (white crystal sugar)
• 1 flat teaspoon of vacuum dried yeast

IMPORTANT: NEVER completely fill the reactor! The reaction may result in a foamy surface which contains a lot of yeast fungus and bacteria. Make sure there is always a distance of 5cm between the water level in the reactor and the connecting piece.

In case you didn't follow this advice and got the yeast brew in your tank, change 50% of the wather and another 50% one week later in order to remove the high amount of organic waste.

After 2-4 weeks or when the reaction slows down significantly, refill the reactor. The old brew is not harmful to the environment and can go down the drain (or you can destill it and make a really nice liquor ;)