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Procedure for adding more CO2

Discussion in 'Talk to Tom Barr' started by scottward, Jun 23, 2009.

  1. scottward

    scottward Guru Class Expert

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    Hi,

    My CO2 is fed into the intake of a powerhead that I have blasting the mist along the length of the tank (powerhead output aimed roughly at the centre of the front glass). This results in a 'champagne' effect in my tank and most leaves in the tank swaying in the current - which I believe is 'what I want'.

    I have a 6' tank (400 litres) with 240watts of light over the top. Just last week I replaced the lights with brand new ones so I know my lighting is good.

    I am also dosing full EI, so nutrients good.

    Plant growth is still not real crash hot and there are various forms of algae popping up here and there.

    As Tom always suggests to look at CO2, and I believe I've ruled out light and nutrients as a factor, I am gradually cranking up my CO2.

    What is the best practice here?

    I am thinking the best practice is to:

    1. Increase rate of CO2 slightly
    2. Observe plants/fish for 1 week
    If plant growth/algae issues haven't improved and fish are ok repeat step 1-2
    If plant growth/agae issues haven't improved and fish are gasping this means:
    - maximum CO2 is in the water back off CO2 slightly
    - issue with plants isn't CO2 related, i.e. CO2 ruled out by maxing it out
    If plant growth/algae issues improve after 1 week, stop.

    Scott.
     
  2. scottward

    scottward Guru Class Expert

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    By the way,

    My CO2 is turned up so much at the moment that the bubbles are totally uncountable in the bubble counter - just a very rapid stream of gas.

    Is this normal?

    Using the intake of a powerhead isn't too bad a technique is it? i.e. not super inefficient?

    Scott.
     
  3. shoggoth43

    shoggoth43 Lifetime Charter Member
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    The powerhead/needlewheel is probably one of the more efficient methods for getting usable CO2 and the added flow to help distribute it around the tank. It may not be the most efficient though. You should not "need" to have an uncountable bubble amount so that seems odd. Bear in mind that it takes some time for the plants to adjust to different levels of CO2 so it may take a few weeks for you to see some turn around. How is the surface ripple on your tank? Perhaps you have too much and are just blowing off the CO2 nearly as fast as it's added?

    -
    S
     
  4. Philosophos

    Philosophos Lifetime Charter Member
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    Needle wheel is working out great for me.

    I'd say you can go more agressive with the CO2. I adjust mine once or twice a day until the drop checker looks good and the fish aren't stressing. I do find it ends up with a bit of an algae spike this way, but the job gets done much faster. From there, just watch the plants, fish and algae to see where you should go.

    -Philosophos
     
  5. scottward

    scottward Guru Class Expert

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    There is absolutely no surface movement at all, it is very still, so I'm not blowing off the CO2. My tank is 100 gallon - for a tank this size perhaps I do need such a fast bubble rate?

    How large is your tank? We need to compare apples with apples.
     
  6. Gerryd

    Gerryd Plant Guru Team
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    Hi Scott,

    I have a 180 and until just recently I was going through a 10lb bottle in 4-6 weeks max.....My rate was like yours and was totally uncountable.

    I since changed to a different pump and reconfigured my plumbing some and am now at about 10-12 bubbles per second and my growth is great and no algae.

    Based on what I WAS doing, I knew something was wrong but could never figure out what it was.

    Based on that I would say you could use a more efficient method or better dispersal in the tank.

    Something is not right if you use that much c02......

    That is a good plan but you may be able to adjust 2x weekly and monitor for 3 days at a time. Just adjust the rate a bit at a time.

    I have found that even after a week of so of monitoring that some aspect may cause a change (clogged filter, etc) and may cause fish distress.

    Not sure you can say that just because the fish gasp it means that you have enough c02 and your growth or algae issues are not c02 related. I think in many cases this could be true, but the more I learn about c02 and the planted tank, the less sure I am of anything :)

    I was always trying to get my drop checker into yellow or a nice green. Now I am just watching the plants, algae, and fish and seem to have better stability.

    I can only assume that I was pushing WAY TOO MUCH c02 into the tank in a single minded pursuit of pearling and a good DC color.

    I came to this one day recently after I switched my pump. MY c02 tank was empty and the refill place was on vacation and closed. Yet, 3 days later I still had pearling????? So this got me thinking and I started with a bubble rate of 5-6 per second and went from there.

    We'll see how long the 10 lb bottle lasts now, but I would say by rate is hundreds/thousand fold LESS than I was doing before.

    Hope this helps.
     
  7. scottward

    scottward Guru Class Expert

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    10lbs, that's about 4.5kg. I have a 2kg bottle and my tank is approximately half the size of yours. I think I will probably chew through this bottle a lot faster too, now that I have cranked it up a lot more.

    You've probably already mentioned the details, but just quickly, what changes did you make to your pump/plumbing? Could it just be a co-incidence, or do you really thing you have found a much more effecient way to get the CO2 into the tank?

    This is what has got me banging my head against the wall. The lighting is fine (to be doubly sure I just recently put in new tubes). I am dosing full EI. Only thing left is CO2. So the only thing I can really do is keep adding more and more and more and more until things look better!


    Doesn't it take a week though for the plants Rubisco to adjust? So doesn't this mean that for every CO2 change that is made, at least one week will need to elapse before any noticeable change in the tank will occur?

    Understand.

    No wonder people give up on this part of the hobby! It is so ridiculously complicated and confussing. If after another couple of weeks of hammering the tank with CO2 my plants don't start taking off then I really can't see any point continuing as I have, as far as I can see, ruled everything out and tested everything! If there is some obscure, unique characteristic of my tank that is the root of all my problems I am never going to find it. ;-)

    I have removed my drop checker. I hate it. ;-)

    Is it actually possible to harm the plants with too much CO2?

    As a side question - at the typical temperature of say 25 degrees C, what is the maximum possible ppm that CO2 can get too? At this maximum will it actually start to become toxic to plants?

    That doesn't make any sense - how could the plants still pearl with no CO2 going into the tank for 3 days???? ;-)

    Thanks for taking the time to help me out.

    Maybe I just need to be patient.

    Scott.
     
  8. Tom Barr

    Tom Barr Founder
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    Partly, but good frequent water changes(try this 2x a week, dose thereafter), and really focus on clean filters, good current and good CO2.

    Adjust and tweak things.
    Raise the light a little.

    I found one tank started doing much better once I added a bit more light and the plants finally started growing faster. Later, I reduced it back down.
    The plants had finally started growing like mad and took over.

    CO2, light/nutrients are what the plants need, this takes some time, typically not more than a few days to get going, but do not stop there. Keep on top of it for the next 2-3 weeks and things will really clear up. Once you do this extra added work, then the pay off is you can start to take it much easier.

    Poor CO2 seems to knock the whole system back.

    YME's log on his tank was similar to a tank I recently fixed. Took me awhile and the test parameters alone did not suggest anything was wrong, I even did 2x a week 70% water changes, etc. It was CO2 and giving it some time, cleaning the filter sponge, added a mechanical filter, changed the flow some, added more light for a bit, then reduced it later after I had plenty of biomass and now the tank is jamming along great.

    I had similar dusty algae, floc, detritus floating around, lack luster, but semi okay growth.

    I suggest a more holistic approach, there are unique issues that each aquarium has that is outside the plant species, CO2, light, nutrient dosing. In person we might catch these when helping folks, on line, this is very difficult.

    While 95% folks might be helped with typical advice, I'd like that remaining 5%.
    So such challenges are worth while, both to the aquarist and person helping.

    Regards,
    Tom Barr
     
  9. shoggoth43

    shoggoth43 Lifetime Charter Member
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    I'm running a 30 gallon at the moment. There is noticeable surface agitation, but it is a covered tank. I'm not sure how much air movement is in the tank. I'm currently at 3-4 BPS. BPS is roughly comparable unless you have the same bubble counter I do and use the same diffusion method.

    Based on Gerry's posts, we're probably very similar in the overall amounts he and I are using per gallon. Current flow is a big wildcard though.

    -
    S

     
  10. scottward

    scottward Guru Class Expert

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    Hi Tom,

    Thanks for the reply.

    I can understand the good current/CO2 bit. But, what exactly is the point of the very frequent water changes and rigourous filter cleaning? Will this actually solve my problem?? Could it be that a 50% water change each week is already too much for my tank?

    If there weren't any fish at all in my tank, and I could dose and inject CO2 to extremely high levels, would this actually be bad for the plants?

    I'm thinking of taking the fish out and just absolutely blasting the tank with a super dose of everything!

    Scott.
     
  11. Gerryd

    Gerryd Plant Guru Team
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    Scott,

    Frequent water changes will add more c02 enriched water, enhance waste and nh4 removal, and add more trace elements to the water.

    It is a big help in battling algae.

    Clean filters and such is all to ensure proper flow, clean water, etc.

    Aquatic gardening has many components as we are trying to mimic what nature does naturally. Since all components are related to the tank, any one of these may have an adverse affect.

    I think you need to look into a better c02 dispersal method.

    Your plant pic shows classic c02 symptoms with the poor growth and algae.

    I think you are adding a lot via the bubble count, but it is either not mixing well with the water, you have a leak somewhere, or it is just escaping into the atmosphere too quiclkly to be of use to the plants.

    There should be no reason to have such a high bubble rate.....

    What I changed on my setup was to add another outlet. I had 3 paralell legs from the filter and combined them back to ONE LINE for the output to the tank. I made TWO outlets of a larger size and ran one each to each outlet.

    This gave better flow/current and reduced the back pressure on the filters, venturi, etc.

    Will post more later as I am on lunch and short of time.
     
  12. Tom Barr

    Tom Barr Founder
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    I've never heard or seen any evidence that doing more water changes hurts anything.

    It will only help.

    I do my WC's about 30-60minutes after the lights come on or right when they do.

    It can take a little while for the plants to bounce back and start growing well, once they do, only then will the tank "Right itself". Many seem to expect good CO2= immediate results.

    In some cases........yes.
    But a few......... no, it takes longer.
    Maybe 2-4 weeks.

    YME's thread was similar to a 120 Gal I had and recently fixed. YME had a very similar issues but is likely unconvinced it was still a CO2 issue.

    So was I many times also.

    However, I have a similar tank, T5's 120 Gal etc, packed full of plants that just did not balance well...........I have other tanks that get the same routine , same ferts, WC's, filter cleaning(more on this one), but always had a few plants with lack luster growth, a bit of algae here and there, a bout with GDA........everything else seemed in line.............the other 4 tanks where all doing well also.

    I had to slowly adjust the CO2 by eye.
    I did a diffuser and also injected the CO2 into the intake of the return sump, which also went to a canister.

    The sponge prefilter clogged a lot, the overflow still degassed.
    The CO2 was really touchy and would gas the fish some if I added what I thought was "enough" CO2.

    Some fish where fine, others where not.

    I upped the light for a bit and did a few WC's, and slowly made sure the CO2 was that first 1-2 hours.

    That time span seems critical.
    Good consistn flow through a filter also seems critical.
    Good stable rate of degassing also makes dialing in a good CO2 much easier and is critical.

    It's not about just adding more CO2.
    Other things influence the CO2 ppm's.

    Flow rates through filters affect it(my OC filter micron filter clogged weekly till I started cleaning the sponge filter in the sump more often.
    Light intensity affects it.

    I clean the sponge prefilters often now.
    I ramp the light up, get the plants filled in and growing well, then back off.

    For that tank, that's what works.

    Still, from this and my other tanks, it's safe to say the root issue was CO2.
    It was not the light so much, it was not the sediment nor the dosing of NPK/Traces, it was not the WC's, but the WC seemed to help when done back to back and right when the lights came back on.

    More work, but kicked things into high gear.
    You can also add Excel etc to this, spend more time tweaking the CO2, adding more current but not breaking the water's surface.

    If you have just one tank, then you often do not see things this way, you think I'm crazy, but these other things often are the causes for the CO2 issue/s.

    It's not just an issue of adding more/less gas.

    O2, filters, degassing, current, time to get good CO2 as the gas comes on, light intensity etc etc etc.............

    Now most would not bother to look or consider these other CO2 related issues unless they first knew a priori, that the other things like dosing ferts, light, etc, are independent and thus not a factor.

    Unfortunately many are not so sure and run after their tail looking for these other factors. How can it be the case when other tanks have that and no such issues?
    and hence, folks will have plenty of disagreements and blame to go around.

    That approach however does not solve anything at the root.
    Which is much more interesting and important.

    Regards,
    Tom Barr
     
  13. scottward

    scottward Guru Class Expert

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    Hi Tom, thanks for the advice.

    This is interesting. Have a look at my other thread where I mention that my H.Polysperma leaves are drooping within the first few hours of lights on. This seems to correlate with what you are classing here as a critical time. Should I be putting my CO2 on more than 1 hour before the lighting? I would have thought that 1 hour would provide plenty of time to get the CO2 level up?

    What exactly is degassing? Does this mean the process of the CO2 leaving the water? i.e. to help with stability CO2 should leave the water at a constant (read 'stable') rate?

    - Light intensity
    - Water temperature
    - Surface turbulence
    - Anything else? Is there any other 'chemical' that can be in the water that can affect it?

    Can you explain this to me - I don't understand what you're talking about? What is a priori? ;-)

    Tom, thanks for pointing me to YME's thread. I had a good read of it, and it was interesting. Looks like we are facing similar challenges although YME's tank looks 10,000 times better than mine!

    I note that you mention cleaning of the filter a lot. Is this only really of such focus when using the filter as the primary means of circulation? I am not using my canister filter anymore for circulation. I am feeding my CO2 directly into the intake of a powerhead and using the powerhead to spray the CO2 into the tank and for circulation. The canister filter is really only there for the biological filtration.

    Scott.

    P.S. Can you please help me with some advice on what should be a typical bubble rate for my 100g tank using the powerhead for CO2 injection with 240W of light? As I've mentioned previously, my bubble rate is so high at the moment that the bubble counter is bubbling away like mad. Is this 'normal' based on the injection method that I am using? I am going through CO2 bottles very fast but am not sure if this is just normal and that all along my problem has been being to conservative with the gas, or, if I really am wasting it.
     

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