DIY CO2 Generators 

Information can be found all over the web on how to generate CO2 using yeast. I am currently using this process to provide CO2 for my plants. Here is a list of items used to create my CO2 generators.

1)  2 x  2-Liter soda bottles

 2)  1 x  20oz  soda bottle

3)  4 ft of air line

4) 2 x air line check valves

5) 2 packets of yeast ( 1 per bottle)

6) 2 1/2 cups of sugar

7) 1 x gravel vacuum tube

8) appox. 10 1" bio balls

9)  15 cups of water 

I use 1 1/4 cups of sugar mixed with 6 1/4 cups of water and one yeast packet per each 2-Liter bottle. I drain and remix 1 of the bottles every 2 weeks. I also shake the 2 week old bottles when refilling the other.   

Here is the system installed in my sump.

Here you can see the check valves and the 20oz soda bottle. The check valves prevent tank water from siphoning from the tank into the bottles. The 20oz soda bottle acts as a trap preventing foam or liquids from entering the tank and also keeps the lines clear for the CO2 to flow.

 

When I first setup the tank I did not install the CO2 generators. I  was using treated tap water. It was very hard water which gave the plants plenty of minerals. Although they did not grow very fast they managed to stay alive. Once my RO/DI unit was installed and the water was replaced with soft water the plants did not have the necessary minerals and began to turn brown and die off. Since introducing CO2 they have regained their health and have grown 4 to 5 new leaves within a week. 

DIY CO2 Reactor

 If you want a large amount of CO2 to absorb in the water this is one of the best ways. There are some reactors or diffusers you can buy that work great and may even work better. For the money this was the best alternative. I already had a unused gravel tube, sponge pad, and bio balls. The black air line was $5.41 and the PVC fittings were $1.58, so I spent about $7 total.  Way better than  $50-$80  for  most of the  retail reactors.

Most reactors on the web use vinyl tubing coming from the pump to the top of the reactor. I needed a reactor to hook up to 3/4 inch PVC plumbing. Here are the parts I used to make my reactor:

1) 1 x python gravel vac tube

2) 1 x filter sponge pad

3) 12 bio balls

4) 1x PVC 1 1/2 to 3/4 bushing

5) 1 x PVC 3/4 slip to 3/4 spigot elbow

 First off you will find that the gravel vac tubes are not a standard size. To keep the size down I elected to have the adapter bushing insert into the tube instead of outside of it. A 1 1/2 PVC bushing sanded down slightly will insert into the vac tube. I have access to a lathe and used it to turn down the PVC bushing. For looks I turned down the entire bushing including the hex head. I also shortened it slighlty.  After getting the bushing to fit into the vac tube I assembled the reactor and drilled holes for the air lines.

 I used black air line for the reactor and decided to change the existing generator air line to black also.

 I then installed the reactor in the refugium. The reactor works great. My plants are growing very quickly now and looking much better. Here are few pictures.

 After installing the RO/DI unit I replaced the treated hard tap water with soft water. With the hard tap water and no CO2 the plants where doing ok but did not growing any new leaves. They were using the minerals in the hard water because of the absence of CO2. When I changed to soft water with no CO2 the plants began to die.  With CO2 and no reactor the plants came back and grew a few new leaves but were still not growing very fast. After the reactor was added they began sprouting new leaves every day or so and began growing very rapidly.

This picture is one week after the reactor was installed. Notice the spotted dead leaves have been trimmed off and new leaves have been grown.

Updated 08-02-07 New refugium picture