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How to Make a C02 Reactor and Diffuser for a Planted Fish Tank, DIY

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  I have had a lot of friends asking how I keep my aquarium plants so green and healthy. The trick is to have good lighting (around 1.5w per gallon) and carbon dioxide to help your plants grow when that good lighting is on. So instead of answering everyone individually I thought I would write up this little DIY on making a homemade C02 reactor for your planted tank.

  It's simple and easy to make and best of all it's cheap! It works exactly the same as the $50 reactor they sell at petsmart without the high price. This C02 dispenser should take about 15 minutes to make and uses easy to come by supplies.


Materials and Tools

  • +/- 5' of clear 1/4" silicone tubing
  • One quart size Gatorade bottle
  • One Chopstick (Get them from your local chinese restaurant for free)
  • Sugar
  • yeast (Buy the individual packets)
  • Scissors
  • Drill and drill bit
  • Check valve (Optional)

    All the materials can be bought at your local Grocery store besides for the Tubing, check valve, drill and bit. The tubing can be bought cheapest at a hardware store or at pet store for a couple dollar. Borrow your neighbors drill if you don't have one and you're ready.

Let's Get Started!

Gather up your supplies and start drinking your bottle of Gatorade so we can get this reactor made!!

  • Clean out your Gatorade bottle with soap and water or home brewing sterilizer if you plan on drinking your reactor juice (I'll get into that later).
  • Place your Gatorade cap on a block and with a 3/16" drill bit, drill a hole right through the center. If you use a drill bit equal to or larger than your tubing you will have to use caulk to make it airtight. That's just a hassle, so make sure your drill bit is smaller than your air tube.
  • Cut your tubbing at a sharp angle so you can get it in the hole. With a pair of pliers pull about an inch through the hole. You should now have a tighter seal than a virgin on prom night. So cut off the extra tubing about a centimeter from the inside of the cap.

  • On the opposite end of your tube you have a wide variety of diffusers that you can use. There are a ton of different air bubble stones from the pet store ranging from wood to ceramic that come in many different shapes and sizes. Glass diffuser's that can be bought on ebay for about $4, or my favorite, the free chopstick.
  • Prom and the after party are over so grab your chopstick and push about a inch of it into the tubing. It should be a tight fit but your carbon dioxide will work its ways through the pores of the wood and give you nice small bubbles.
  • With a pair of sharp scissors or a butcher knife cut the chopstick at the end of the tube.

Now for the Magic Elixir.

Your reactor is now done you just need the fuel to run it. Which I will give you the recipe for $14.95. Ok I'm joking. $12.95, No?. Fine for free. Your reactor runs off of a sugar and yeast mixture, it is basically the same method used to make any alcoholic beverage. The yeast causes the sugar to ferment and the gases being created from that process is carbon dioxide.

For your Gatorade size bottle I have found that the best ratio of sugar to yeast has been 3/4th's cup of sugar and 1/4th teaspoon of yeast. Now with those measurements lets make some gas without rippin ass!

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  • In a shot glass put in your 1/4th teaspoon of yeast and fill it to the rim with warm water. That will help the yeast activate before mixing it into the sugar water.
  • Pour your 3/4th's cup of sugar into your Gatorade bottle and fill it about halfway with warm water. Now shake, shake, shake till the sugar is diluted in the water.
  • After about 15-20 minutes the yeast will be forming a foam on top of the shot glass. It's telling you that it's ready. So pour it into your sugar and water mixture. If there is any yeast at the bottom of the shot glass just add some warm water and pour it into your gatorade container.
  • If at this point your Gatorade container is full up till when it starts sloping inward then you are done if not then add warm water to that point and shake, shake, shake.
  • Screw the lid on cause you are done.

The mixture should last for about two through three weeks. At that point make up another batch and you're good to go.

Depending on what type of diffuser you decided to use and where you placed it you will need to clean it off. I Replace my chopstick every other time that I replace my mixture. That seems to keep it clean and keep the co2 bubbles flowing. As for placement I shove the tube up the out tube of my canister filter which works very well for mixing the c02 in the water. Experiment with your own set-up and you will find what works for you.


Can I Drink My Juice?

  Someone always wants to know if they can drink the mixture. Yes you can. Just make sure you sterilize your bottle before you start and another good idea would be to put a low psi check valve into your tubing so only the gas goes out and nothing can come back into your mixture. After you make another batch of c02 juice make sure you don't store your old mixture with a closed lid. Drill a hole in another gatorade cap and stick a check valve in it so your stored juice can release pressure as it builds. If you don't let the pressure out it will explode the bottle.

  If you do plan to drink it be creative add a cinnamon stick or some fresh cut ginger. Maybe a little orange peel. Just make sure you sterilize your bottle and use a check valve or you will have a hangover far worse than when you drank your friends homebrew.


Writen4u (author) on January 03, 2013:

It usually takes between 12 and 32 hours I'd say. On average my bottles usually start around 12-14 hours.

Hector on January 01, 2013:

And how long does it have to sit before it starts releasing bubbles or carbon dioxide better yet

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