co2 diffuser, what do you think??

  1. Dang Well Known Member Member

    Hi all this is my idea for a do it yourself co2 diffuser. I'll be using the output of my canister filter a siphon hose and siphon tubing. I drew a picture which you can see. It will be the output filter.....the siphon hose plugged into that....then that plugged into the siphon. The outflow of the filtered water will rush in into the siphon hose. It will be at the same angle pointed downwards as if you were doing a water change. The co2 tube will be running in from the bottom. The diffusing will take place inside the siphon tube and hopefully go into the aquarium out the bottom. I've been getting a lot of "it will move my gravel away" and I know...doesn't really make a difference to me.
    So how does this all sound? I haven't tried it yet.

    Attached Files:

  2. toosie Well Known Member Member

    It looks like it should work fine as long as your syphon tube isn't too short... longer would be better. I'd recommend putting a piece of foam filter media in the bottom of the tube and puncturing a hole in it just large enough to feed the co2 airline through it. It will help to keep the line in place if the foam fits around it snuggly and it will help keep the water flow from just pushing out undissolved co2. If it was me, I would also add bioballs or ceramic discs to help trap co2 giving the water flow more of a chance to dissolve more co2.

  3. Dang Well Known Member Member

    Well as it sits the tube is as long as the side of the tank, I just need to cut it so I can get the top underwater to connect the filter output to it. I also was considering the filter mesh on the bottom thank you for the suggestion. Compared to a powrrhead, which I think would be way too much water pressure, I'm hoping the filter output will be just right. I'm going to try to set t up Monday. Thanks again for your reply. I'll post about how it works when I get it all set up.
  4. toosie Well Known Member Member

    Great! I'll look forward to your next post!

  5. Dang Well Known Member Member

    So today I got the co2 going and it works fantastic! Finally got a good diffuser going. I do need to put a sponge or something on the bottom of the tube like you said though because a lot of bubbles are coming out of the bottom, they are super super tiny though.
  6. toosie Well Known Member Member

    Sounds great. Do you know how to tell when you have 30ppm of CO2 disolved in the water? I'm assuming that is your goal. Most of us with planted tanks try to aim for that amount. Some get brave and aim for more, and others shoot for less so I'm not sure what you had in mind.
  7. Dang Well Known Member Member

    I've never measured before but I'll take your advice and go with 30. I have an idea, isn't it something like testing your pH with and without the co2 and compare?

  8. toosie Well Known Member Member

    Yes. Take a sample of aquarium water and add a bubbler to it. After 24 hours test the pH. Then test the pH of the water in the aquarium. A difference of one full point equals 30ppm CO2. So, if the true pH of your aquarium is 7.4 and the water after CO2 is dosed tests at 6.4 that will mean you have approximately 30ppm of CO2 dissolved in the water.

    It's important to test a degassed sample from the aquarium as opposed to just testing tap water because there are different things present in the aquarium that can affect CO2 so your aquarium water and tap water may not have the same reading.
  9. Dang Well Known Member Member

    Ok thanks for putting it so simple. I don't use tap water anyway. The water I get from the fish store is 6.8 ph I think I honestly haven't tested my water in a couple months.
  10. toosie Well Known Member Member

    If the natural pH of the fish tank is also 6.8, you may want to test the GH and KH. You may need to use a little crushed coral, crushed oyster shells or argonite to increase GH/KH and buffer your pH and bring it up a little more. If you allow the CO2 to bring your pH down the 1 point, to 5.8, the beneficial bacteria may quit working. On top of that, your plants won't do well at that low of a pH. A pH of about 6.6 - 6.8 is about as low as your plants will appreciate. You can try it a little lower but if your plants start to not do well, the low pH is the first thing I would look at.

    Plants also need a certain amount of KH because some KH will be used by the plants for a source of carbon as well as the CO2 you provide them, so an already low KH can place your tank in an unstable position and cause the pH to crash. Testing for GH/KH will tell you if you have anything to worry about so that you can adress the issue before anything bad happens.

  11. leeju Initiate Member

    This looks like a nice DIY set-up! I'm very new to all this, just set up my first ~60g last weekend and have had no success with the conventional glass CO2 diffuser with yeast/sugar reaction. It seems that the pressure of the water near the bottom of the tank is too much for the CO2 to overcome. I considered ordering the plastic ladder diffuser, but I don't want to waste time and money on something that won't work. That, and I don't want three of those buggers hanging on the tank walls!
    I understand the illustration for the output of the canister filter, but I don't have a canister filter and I don't really get how you are introducing the CO2. Should I just bite the bullet and buy the pressurized CO2 system or can you think of a way I can boost the pressure of a DIY CO2 reactor?
  12. Dang Well Known Member Member

    Well I have it hooked to a power head now, so that is putting water into the tube. If you have the bottles at the same level as the tank that seems to help with the co2 pressure being able to overcome the water that has got into the tube.
  13. leeju Initiate Member

    Duh, I never thought of raising the CO2 bottles. Thanks for the info!
  14. Dang Well Known Member Member

    That and make sure your stuff is air tight. At first one of my caps on the bottles, the hole was a pinch too big. I don't use glue or sealant i just cut a hole in the cap and pull the tube through it with pliers, naturally air tight. I replaced the cap with a new hole and have it level with my tank. Good to go now.

    Yours is working?
  15. Mark S Member Member

    I have my hose running into the intake of a power head, if I unhook the hose from the bubble counter the powerhead sucks air through the hose. So my hole system is really working on a vaccum but still sealed so if I go with a airstone I can. My bottles are 20 feet away from the tank (well 20 feet of hose to get from point A to point B) and and 3" from the floor. With 4 bottles going I stay in the light green on the drop checker in my 55g. I also drilled holes in a 5/8" ID peice of pvc and ran it acrosss the back of the tank hooked to the power head to distribute the CO2 evenly throughout the tank.