i used this one, it works very well. copied off another site.
Many hobbyists like to have natural plants in their aquariums. Depending on factors such as lighting and the types of plants you keep, you may need to add CO2 to your system. However, buying a pressurized setup can be a bit costly. In comes DIY (Do-It-Yourself). Even then, some people think that even this method is cumbersome. Well, here we are going to go from start to finish just to show how simple it really is.
Step I: Making the medium (a.k.a Jell-O)
............. Ingredients: 1 pk. Regular 6oz Jell-O. Flavor Optional.
.............................. 2 ½ cups boiling water
.............................. 2 cups pure cane sugar
............. 1) In a large saucepan, fill with water and bring to a rolling boil.
............. 2) Empty (1) 6oz package of Jell-O in a large mixing bowl.
............. 3) When water is boiling, carefully measure out 2 ½ cups.
.............................. a.
CAUTION: Contents will be very hot. Be Careful.
............. 4) Pour water in bowl with Jell-O and mix thoroughly until well dissolved.
............. 5) Pour in sugar and thoroughly mix again until well dissolved.
............. 6) Once everything has been dissolved, pour contents in a flat Tupperware container.
............. 7) Cover and place in refrigerator.
Step II: Making the Reactor
............. While the Jell-O is setting up, let’s make the reactor vessels.
............. Materials: 1 64oz Juice bottle (Ocean Spray seems to be best)
........................... 1 1pt bottled water bottle
........................... 4’ CO2 tubing
........................... GE Silicone I caulk (optional)
............. Tools:
..... Cordless drill w/ bits
........................... Scissors
........................... Case Knife
........................... Needle Nose Pliers
........................... Toothpick
............. 1) Start by thoroughly cleaning both bottles with hot water.
............. 2) Remove lids. Drill a 3/16 hole directly in the center of the juice bottle lid. Drill two holes in the smaller water bottle lid.
............. * NOTE * For best results, start with a small drill bit to create a pilot hole. Then using other bits, work your way up to 3/16. The 3/16 size is a fraction smaller than the diameter of the tubing and will provide for a tight fit.
............. 3) Using the case knife, carefully trim any shavings left by the drill bit.
............. 4) Measure about 2’ of tubing.
............. 5) Using scissors cut one end of the tube at an angle.
............. 6) Push the angled end through the top of the cap.
............. 7) Using the pliers, grab the end and carefully pull the tubing the rest of the way through the cap.
............. 8) Cut off the angled end to make a flat cut.
............. 9) Slowly pull tubing out of cap until about ¼” remains in the cap.
............. 10) Repeat steps 5-8 with the opposite end of the tubing into one hole of the water bottle cap.
............. 11) Test fit tubing in water bottle and adjust length if needed. There should be a bend in the tubing.
............. 12) Using the remaining length of tubing, repeat steps 5-9 using the second hole on the water bottle cap.
............. 13) Caulk around all three pieces of tubing on the inside of the caps using GE Silicone I caulk only. This is an optional step as the seal around the tubing will be sufficient with the 3/16” hole depending on how you diffuse the gas. I didn’t do this at first until I switched to a glass diffuser, which resulted in needing higher pressure. In one setup, I discovered a leak in the separator bottle so I added the silicone.
............. 14) Use the toothpick to spread the caulk completely around the tubing to ensure the entire area is covered.
............. 15) Set caps aside and let silicone cure at least 24hrs.
Step III: Time to make gas
............. Now that our Jell-O has set and our reactor vessels have been made, it is time to start making gas… CO2.
............. Ingredients: 1 tsp Bakers or Brewers Yeast divided
.............................. ¾ tsp for initial setup
.............................. ¼ tsp to add later
.............................. ¼ tsp. Sugar
.............................. ¼ cup hot water
.............................. ¼ tsp. Baking soda
.............................. Air stone (diffuser)
.............................. * NOTE * use a limewood airstone or glass diffuser for best results
............. 1) Activate the yeast. In ¼ hot water, dissolve ¼ tsp sugar. Stir thoroughly.
............. 2) While water is still spinning from step 1 (tornado effect as I like to call it), carefully pour in ¾ tsp of yeast. This will help in prevent clumping.
............. “snow globe” effect shows the yeast activating:
............. 3) While this is activating (appox. 15 minutes), cut Jell-O in small cubes. The small cubes allow for more surface action for the yeast.
............. 4) Add the cubes to the large bottle.
............. 5) After yeast has activated (again allow approx. 15 minutes), add 2 cups hot water to Jell-O bottle.
............. 6) Pour yeast mixture into bottle.
............. 7) Add ¼ tsp Baking Soda.
............. 8) Using hot water, fill bottle until you have approx. 2” free space from the lid.
............. 9) Add remaining ¼ tsp yeast.
............. 10) Fill seperator bottle with water about 3/4 full. Water should be over the end of the curved tubing. This will enable you to see and count the bubbles.
............. 11) Cap both bottles tightly. Remember to allow for a “curve” in the separator bottle.
............. 12) Within hours, you will start to see generation of CO2.
That’s all it takes. Now go grow beautiful and healthy plants.
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* EDIT *
I have since changed a couple things on this original design basically due to the pressure that builds up.
1) Replace the water/soda bottle that is used as the gas seperator bottle with a 20oz Gatorade bottle. These bottles provide a much tighter seal.
2) Caulk both top and bottom of the caps around the CO2 tubing.
