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Co2 injection: What's the most efficient method?

Discussion in 'CO2 Enrichment' started by fablau, Jan 2, 2015.

  1. fablau

    fablau rotalabutterfly.com
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    Hello everyone.

    I am aware there might be several threads on these forums around this subject, but instead than introducing my specific questions on old discussions, I'd decided to open a new thread. I hope this is ok for everyone!

    Here is my question: What of the following methods, in your opinion, are the most efficient, and therefore the "best", for diffusing Co2 in the tank?

    1. Ceramic Diffusers.

    2. In-Line reactors (i.e. AquaMedic 1000)

    3. Needle-wheel pump

    4. In-Line Atomizer Diffusers like this one:

    http://www.co2art.co.uk/collections/diffusers/products/original-up-new-inline-co2-atomizer-diffuser-system-16-22mm-hose


    I know that Ceramic Diffusers might be the less efficient ones, but I am not sure between a reactor and an atomizer. I have always been using reactors coupled with a Cerges, with or without needle wheel pumps, and I could reach a pretty good efficiency, but I am wondering if atomizers like the one at the link above could be even better in diffusing Co2 into the tank?

    Any thoughts on this subject are very welcome!

    Thank you in advance, and Happy New Year!

    All the best,

    Fab.
     
  2. Tom Barr

    Tom Barr Founder
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    Reactors tend to be 100%.
     
  3. Pikez

    Pikez Rotala Killer!
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    Hi Fab - good question. I think the answer is a combination of methods.


    I've spent a lot of time and money this past year to increase the efficiency of my system. My goal was to drop the pH by 1.0 in 1 to 1.5 hours and KEEP IT THERE all day. Given I'm dealing with a 180 gal tank, this is not easy. I've achieved my goal with the system described below.


    Due to physical constraints, I'm unable to do the now-preferred overflow/sealed of wet-dry/sump solution. So I've got two large canister filters and two of everything. Everything in parallel. Two needle valves, two bubble counter, two Sera Flore 1000, two cerges 20" x 4" reactors filled with bioballs. When the CO2 times kicks on, the CO2 flows thru the bubble counter like turbo-charged leaf blowers for an hour…and the pH has dropped from 7 to 6.0 and I have no issue keeping it steady for the rest of the day. I don't have much flow but the capacity is huge, so every bubble dissolves. My system and CO2 levels are actually overkill, but I wanted to completely rule out CO2 as a cause for issues. Check! The urban myth is true: algae is GONE! I don't know what to do with myself. I need a new enemy.


    I think my method is very similar to yours - inline-reactor + cerges. All the commercial in-line reactors are woefully undersized. There should be a Sera Flore 2000 or better yet, sized like my cerges for EI + high light folks. I've used and ceramic diffusers and in-line atomizers - discarded both, as they were underpowered for big tanks with high light.


    - - - Updated - - -


    Hi Fab - good question. I think the answer is a combination of methods.


    I've spent a lot of time and money this past year to increase the efficiency of my system. My goal was to drop the pH by 1.0 in 1 to 1.5 hours and KEEP IT THERE all day. Given I'm dealing with a 180 gal tank, this is not easy. I've achieved my goal with the system described below.


    Due to physical constraints, I'm unable to do the now-preferred overflow/sealed of wet-dry/sump solution. So I've got two large canister filters and two of everything. Everything in parallel. Two needle valves, two bubble counter, two Sera Flore 1000, two cerges 20" x 4" reactors filled with bioballs. When the CO2 times kicks on, the CO2 flows thru the bubble counter like turbo-charged leaf blowers for an hour…and the pH has dropped from 7 to 6.0 and I have no issue keeping it steady for the rest of the day. I don't have much flow but the capacity is huge, so every bubble dissolves. My system and CO2 levels are actually overkill, but I wanted to completely rule out CO2 as a cause for issues. Check! The urban myth is true: algae is GONE! I don't know what to do with myself. I need a new enemy.


    I think my method is very similar to yours - inline-reactor + cerges. All the commercial in-line reactors are woefully undersized. There should be a Sera Flore 2000 or better yet, sized like my cerges for EI + high light folks. I've used and ceramic diffusers and in-line atomizers - discarded both, as they were underpowered for big tanks with high light.
     
  4. fablau

    fablau rotalabutterfly.com
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    Thank you for your replies guys, you just confirmed what I guessed :) So, I am probably already at the top of the efficiency with my setup, but as you wrote Pikez, it is hard to let the Co2 drop fast and KEEP IT THERE without going down too much! That's the point...


    For example, have a look at the following shot from my Apex:


    https://www.dropbox.com/s/r7ol74h3c3retkj/PHdrop.jpg?dl=0


    It shows my current PH drop from 10am. It takes about 2 hours to drop 1 point... and then stabilizes at around 1.2-1.3 PH drop. The fact is, if I increase Co2 it drops faster, but the PH also drops much more which I don't want (and I don't need). The ideal curve would be: fast drop of 1 within 1 hour, and then another hour or so to reach the desired 1.2 drop and keep it there until the end of photo period... but I am unable to do that. As you can see from the graph, after the first 2 hours of dropping about 1 point, it takes additional 2 hours and 1/2 to reach the desired 1.2 PH drop. But I have a wet/dry...


    Looks instead you are able to achieve what I'd like! Am I right?
     
    #4 fablau, Jan 2, 2015
    Last edited by a moderator: Jan 2, 2015
  5. Pikez

    Pikez Rotala Killer!
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    Yes…with some hesitation. I can definitely drop the pH to where I need it in an hour by seriously cranking open the gas flow. But my tank is also fish less. I also have a pH controller but then there are associated issues with calibration and probe accuracy/malfunction. I maintain CO2 levels that are very uncomfortable for fish. Don't plan on keeping it that way permanently, but just long enough to experiment in a system where low/fluctuating CO2 is not an issue. Turns out (gasp!) that there are issues besides CO2. :)


    Looking at your graph, I think you should be fine. It is somewhat table-shaped, which is what I assume you want. I wouldn't sweat the last 0.2 drop. I think a lot of people never reach the levels they need or finally reach it at the end of the day…?


    - - - Updated - - -


    Yes…with some hesitation. I can definitely drop the pH to where I need it in an hour by seriously cranking open the gas flow. But my tank is also fish less. I also have a pH controller but then there are associated issues with calibration and probe accuracy/malfunction. I maintain CO2 levels that are very uncomfortable for fish. Don't plan on keeping it that way permanently, but just long enough to experiment in a system where low/fluctuating CO2 is not an issue. Turns out (gasp!) that there are issues besides CO2. :)


    Looking at your graph, I think you should be fine. It is somewhat table-shaped, which is what I assume you want. I wouldn't sweat the last 0.2 drop. I think a lot of people never reach the levels they need or finally reach it at the end of the day…?
     
  6. ltb420

    ltb420 Lifetime Members
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    Here is my graph I also have a wet dry lights kick on at 8am and ramp up to full brightness by 10:30am. [​IMG]
     
  7. rjordan393

    rjordan393 Guru Class Expert

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    I use a 3 inch diameter home made pvc reactor filled with bio-balls. The body is 43 inches tall. It dissolves all the bubbles. In about 2 hours or less, my pH drops from 7.20 to 6.40. The reactor is fed by a "Marineland 350 magnum canister filter. The tank is a 75 gallon but I estimate it actually holds 65 gallons. Adding the bio-balls creates more dwell time to allow complete dissolving. The size of the reactor also plays a role too.


    But I think the bio-balls may become slimed up in the same way the hoses do. if that happens, then I will have to find an efficient way to clean them or forget about using them.
     
    #7 rjordan393, Jan 2, 2015
    Last edited by a moderator: Jan 3, 2015
  8. fablau

    fablau rotalabutterfly.com
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    Wow, thank you guys! I appreciate your posted info. I see I am pretty much like you, therefore I should be good :) ltb420, looks like you are pumping a lot of co2 to drop over 1.4!! I use about 70ml/minute in a 75gl tank, and I think to use it a lot already....
     
  9. ltb420

    ltb420 Lifetime Members
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    I could never do that with a canister. When I was running two canisters on that tank I could drop the PH 1 point in under an hour but the fish would all be gasping at the surface shortly after. I am running just over 70ml a minute of CO2 into a 75 gallon also. I have tried to reduce it but have gotten negative results. The best part about the wet dry is how much O2 you are adding, that gives you some extra wiggle room.I have further dialed in the tank by adding a lilly pipe type adapter to the out flow. This disperses the water more creating a much more laminar flow. Now my plants are just gently swaying and I get much more pearling.
     
  10. fablau

    fablau rotalabutterfly.com
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    I agree with you, of course. Now I am also testing additional aeration at night with an extra circulation pump directed to the surface, and so far so good. It has been just a few days, but I already see a better growth in some plants (mostly Anubias), and happier fish of course. I am trying to get rid of a few BBA around the tank, mostly on slow growers like Anubias and a few others, and reading around seems that could help. Also, my sump is very well sealed, therefore O2 could have been a little low, and if you also add the fact my tank and substrate are pretty old (over 5 years), organic load must be pretty high, and looks like more O2 can help with several issues on that side (more stable environment, better for bacteria, etc.)


    I will post results of this experiment in a week or so.


    Do you have a well sealed sump? Do you aerate at night?
     
  11. ltb420

    ltb420 Lifetime Members
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    Yes sealed sump and I do run an air stone at night. I have been trying to find a good quality air stone that produces finer bubbles to add more O2 and off gas CO2 faster.
     
  12. nicpapa

    nicpapa Guru Class Expert

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    I had try your method, with co2 and magnetic valve, but mine was not stable, every other day have diferents bubble rate and the system was unstable.


    The only method that work fine without gasp fish and shrimps is continious co2.


    I run now 10 tanks , with continious co2 , from easy to very dificult plants ....


    at mine big tanks i run air bubble at night.


    In small tanks i use Ceramic Diffusers.


    In large tanks last time i use a


    Cerges Reactor , continious again and it running fine. ( inside the reactor i add a ceramic diffuser , to disolve more the co2 ;) ).
     
  13. rjordan393

    rjordan393 Guru Class Expert

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    Its not the bubbles but surface movement that results in better oxygenation. A power head aimed at the surface will provide more and stronger surface movement then air stones within reason. Even with a strong air pump, the bubbles when bursting at the surface also can or will cause water droplets where you do not want it.


    I once did a series of oxygen tests using a Hach test kit and at no time during the lighting period did my oxygen levels go above 6 ppm. My tank is lightly planted and that may be one of three reasons. The second reason may be the injection of CO2 and the third reason is, I was keeping my tank water at minimal surface movement. I have since changed my opinion about no surface movement during the lighting period and use an adjustable flow power head (low flow) near the surface.


    But the most important thing to know is that it takes my tank 4 to 5 hours to de-gas the CO2 when using a second power head (266 gph) aimed at the surface and raise the oxygen levels higher. When I tested the oxygen level in the morning, it tested at 8 ppm. Now that is the saturation level at about 75 degrees F.


    So how important is de-gassing CO2 and providing more oxygen one may ask? All I can offer is an example such as: why does mold form on tile walls in a shower? Its because of lack of air circulation (oxygen ) to dry the walls when the shower door or curtain is closed. I believe the extra oxygen helps deter some algae species along with giving it back to the plants at saturation level.
     
    #13 rjordan393, Jan 3, 2015
    Last edited by a moderator: Jan 3, 2015
  14. rjordan393

    rjordan393 Guru Class Expert

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    As an additive to my above post:


    I maintain a pH of 6.4 to 6.5 with a carbonate hardness of 3.92 dKH. That gives me a CO2 concentration between 38 to 48 ppm if one uses the online CO2 chart. Now the question is: Can CO2 be de- gased faster at a lower carbonate hardness? If not, then those who drive their CO2 concentration much lower should experience a longer time for it to be de-gased. Whether this matters or not has yet to be determined
     
  15. fablau

    fablau rotalabutterfly.com
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    I agree and confirm what rjordan393 wrote: just air bubbles with an air stone doesn't degas much. Actually I tried to run an air stone in front of my sump main pump intake so that air bubbles were diffused all over the tank during night. I tried that for 15 days, but there was no difference in degassing and I couldn't notice much beneficial effect in plants. As I said, instead now, besides the air bubbles via air stone, I run a small circulation pump inside the tank aimed at the surface, just at night, and now the tank fully degas in about 13 hours, just in time when Co2 starts again (ph 7.5 fully degassed, ph drop to 6.18 at the end of photoperiod.)


    I need to wait a few more days to see if the increased oxygen levels and degassing is actually beneficial to the ecosystem.
     
  16. ltb420

    ltb420 Lifetime Members
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    Co2 injection: What's the most efficient method?


    I also agree the surface movement is what degases the CO2 but an air stone that puts out very tiny bubbles adds more surface area adding more O2. I used to use one of these, the company is no longer around (deep water micro pore) and I have not been able to find a replacement. Keep in mind the demo is in salt water but it also put out tiny bubbles (micro bubbles) in freshwater that would get suspended in the current adding both more surface area and longer contact time with the bubbles.

     
    #16 ltb420, Jan 4, 2015
    Last edited by a moderator: Jan 4, 2015
  17. fablau

    fablau rotalabutterfly.com
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    Co2 injection: What's the most efficient method?


    Wow, that's pretty impressive ! Where could I find that diffuser? What you wrote makes sense, and I am willing to pursue it!
     
  18. ltb420

    ltb420 Lifetime Members
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    With out any extra power heads my CO2 shuts down at 4pm it is now 10pm and I am already at just about a PH of 7. That's a rise of 1.10 in 6 hours


    [​IMG]
     
  19. ltb420

    ltb420 Lifetime Members
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    Sadly the company went under and I am looking for a replacement myself. I will let you know what I find. These were originally developed for the hydroponics industry so I will start my searching there.
     
  20. ltb420

    ltb420 Lifetime Members
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    Fab,


    I am making good progress on degassing the tank after the CO2 period it is now only taking me three hours to get just about there. I found one of the Deep water innovations micro pore stones on eBay quite, pricy now. It is the larger size and at 6" and 1" thick it is quite large. I know Tom has mentioned before that he degases his tank in just about 2 hours and I think with just a few more tweaks I can also get it there. I will try to remove the foam in the trickle tower to get better degassing after the CO2 go's off, I believe more turbulence in the chamber will help degas it faster. I don't think Tom runs the foam either. The plants are all growing much faster, its amazing that just by adding some extra O2 everything has perked up nicely.





    Air stone at work.





    micro bubbles making it into the tank.




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