Does co2 help plants stay alive what does it do??

Discussion in 'Aquarium Plants' started by melovefish, Nov 28, 2012.

  1. melovefish

    melovefishValued MemberMember

    Im really excited about doing live plants for the first time in my 30 gallon aqaurium!!! Im not sure if i need co2 set up or not. I guess what im asking is what does it do and how does it work. People already recommened bulbs and helped lots but it would awsome for some more opioions. If you have live plant aqauriums please share some pics if have them i would love to see them, and this is if you want share how yours is setup and how it works for you.

    any help is greatly appreciated thanks!!! need more info just ask!!!:)
  2. skjl47

    skjl47Valued MemberMember

    Hello; I cannot give any advice from experience as i have not tried CO2 injection. I have, however, grown many tanks of live plants over the decades without such extra CO2 injection.
    So an answer is that co2 injection is not needed to grow plants. It is reported by some to help and perhaps they will give examples of their experience.
    There is a percentage of CO2 in the atmosphere that will also be present in water naturally. The fish and other living things in a tank will give off some co2.
  3. kinezumi89

    kinezumi89Fishlore VIPMember

    Hello :)

    You only need CO2 if you have very bright lights. Plants need three things to thrive: Light, nutrients, and carbon.

    1.The light comes from your lamp obviously; plants have different requirements as to how bright of lights they need to do well. Java fern is almost impossible to kill, while amazon swords need lots of light.

    2. Nutrients are added by you. Either by a nutrient-rich substrate like Fluorite, eco-complete, or even soil; root tabs, liquid ferts, or dry ferts. Plants take up ammonia and nitrate, but they need other things too, like phosphate and iron. Again this depends on how "high-tech" you want your tank to be. In my low-tech tanks I just put root tabs under the root-feeding plants and use liquid ferts (Flourish Comprehensive), but in my high-tech tank I use powdered ferts, because they are more cost-effective in a large tank and it's easier to fluctuate each component (rather than everything being mixed up).

    ((That last sentence doesn't make sense :;smack With liquid ferts, all the components (nitrates, iron, phosphate, whatever is included) is all mixed up in the liquid. If you want to increase the dose, you have to increase the dose of everything. With dry ferts, the components are separated. I don't add nitrate anymore because my fish produce enough of that, but I add extra iron, because I have a plant that likes lots of iron.))

    3. And finally, CO2. If you have very bright lights and lots of good nutrients, then the amount your plants can grow (IE the amount they can photosynthesize) is limited by the amount of carbon they can take up. You only need CO2 added if you have very bright lights and good ferts, because there is naturally carbon dioxide in the water, and that's plenty if you have low lights or ferts (because then their growth is limited by those factors, so no need to waste money adding CO2). If you need to add CO2, you can either use a liquid supplement, or add CO2 gas. The liquid isn't carbon dioxide; it's another compound that the plant breaks down to obtain carbon. Because the plants have to spend energy breaking the compound down, it isn't as efficient as gaseous CO2. If you want to go the gas route, you can either get a cylinder like for a kegerator and inject it in, or a DIY kit involving 2-liter bottes and yeast (yeast consume sugar and produce carbon dioxide).

    Hope this helps! Here are a few pics of some of my tanks :) The one on the left is my 55 gallon with dry ferts, 2x54W T5HO bulbs, and injected CO2. The second tank is a 20 long with just the stock fluorescent bulb and liquid ferts, no CO2.

    Edit: Unfortunately I have to disagree with the above statement. There are certainly many plants that don't require CO2, but some are much more demanding and will not thrive without it. I have a plant (not certain what it is, I received it from a friend) that even with dry ferts and the lights mentioned above, wasn't growing at all. Now that I've added CO2, it's finally putting out new leaves.

    Attached Files:

  4. AlyeskaGirl

    AlyeskaGirlFishlore VIPMember

    In low-light setups CO2 isn't necessary but can be beneficial.

    Moderate light it goes both ways but plants will benefit from it.

    Highlight/high-tech it's required as it increases plant growth to outcompete algae. Balanced fertilizers are also required. All 3 need to be balanced with each other; light, CO2 and fertilizers.

    CO2 makes plants grow better and faster. It's like a fertilizer if you want to think about it that way.

    Link to my planted tank video.


    Tank specs; highlight, no special substrate, root tabs, dose dry fertilizers, 50% weekly water change, injected CO2, 8 hour photoperiod.
    Last edited: Nov 28, 2012
  5. chevyguy8893

    chevyguy8893Well Known MemberMember

    Kinezumi89 and AlyeskaGirl covered this very well already, and they both know planted tanks well.

    So, for comparison, here is two out of my three planted tanks.

    10 gallon, no CO2 other than what is in the water, two screw in CFL bulbs, dosing flourish comprehensive and api leafzone for the water wisteria mostly because it wasn't happy without it. This is an older picture that doesn't look disorganized with java ferns that won't stay down. It is more like a jungle too. Growth is slower, but choosing the right plants for the lighting and tank should give you good results.

    20 gallon, pressurized CO2, EI dosing ferts, high light, moderately planted with mostly faster growing plants (I have some trimming to do). Growth is insanely fast, I have to do weekly trimmings of most of the stem plants. This tank does take more work to maintain, but well worth it.

    The 20 gallon use to be high light and inconsistent CO2 and fertilizers, and it turned into an algae heaven. I lost most of my plants, and then learned very quickly to correct it. I may be biased a bit, but a planted tank is worth the work at whatever light level you have.
    Last edited by a moderator: Nov 23, 2018
  6. kinezumi89

    kinezumi89Fishlore VIPMember

    I always wanted to get rotala indica, but it always looks half dead at the store...not sure if it IS half dead, or just its natural brown color :) Can I ask what the tufts of green in the middle of the tank are?

    I also definitely agree that "high-tech" tanks take more work. First, since there's increased growth, you're constantly gardening and trimming and replanting and such. Plus dosing ferts daily or every other day. I also have to mess with the CO2 because I guess I got a cruddy regulator, so the flow isn't consistent. But I think it's definitely worth it to be able to sit and look at my tank :)
  7. OP

    melovefishValued MemberMember

    all of tanks look amazing!!!! and thanks for of the help VERY HELPFUL
  8. chevyguy8893

    chevyguy8893Well Known MemberMember

    The rotala indica is really nice, but I have found it to be pretty delicate because of a very thin stem. That and they are sold bunched close together breaking a lot of leaves :(. I got mine by chance at a LFS when it came in, but it was all brightly colored yellow and pink coming out of the bag. Hopefully you find some that is healthy, it makes for a nice addition.

    The floating green tufts are bio balls with dwarf riccia netted around it, and they are tie off with fishing line to rocks netted with more riccia. That is what you were referring to right? Basically I ran out of places to put it and now I have more lol.
    Last edited: Nov 28, 2012
  9. RandomZoid

    RandomZoidValued MemberMember

    Since you are a beginner, like me, I would recommend using liquid carbon such as Flourish Excel or API Co2 Booster. I've used both now and thing Excel was more effective at speeding up growth and helping to fight algae.

    If you have over 2 watts per per gallon (rough estimate, depends on type as well), so 60watts over your 30g, then you are going to have algae problems if you don't use Co2 or liquid Carbon.

    I've heard horror stories of valves malfunctioning and waking up to a tank of dead fish so I have stayed away from Co2 so far. I plan to one day turn my 50 gallon into a planted community and will try it then. On my 30 and 10, liquid carbon is doing a great job.
  10. jetajockey

    jetajockeyFishlore VIPMember

    This is a good question that many people ask. When first getting into planted tanks, there can be major information overload.

    To start off, plants need 3 things to thrive. This is the same for terrestrial plants, not just aquatic ones. (Most aquatic plants are terrestrial plants that have learned how to cope with living underwater anyway, but we'll get into that later)

    1) Light - This is the foundation for plants to grow on, so this is the first thing to get situated in a planted tank.
    2) Co2 - Co2 is also used by plants, and is essentia in the growth process.
    3) Fertilizers - Plants also need these to grow. Some of them they use a lot of, we call those Macronutrients, like Nitrogen, Phosphorous, and Potassium (the infamous NPK). Then there are micronutrients, these are things like zinc, boron, and copper. Note that these are only necessary in trace amounts, and can easily be overdosed in a small contained system by someone being careless. There are others that they use in relatively large quantity but we'll just keep it simple now.

    Here's my logic:

    Your light intensity is the key factor in determining growth. It is also the key factor in determining demand on co2 and ferts. So in essence, low light intensity = low demand for co2/ferts, high light intensity = high demand for co2/ferts.

    Watts per gallon is an outdated rule, just like the stocking inch/gallon rule. It's best not to even begin throwing it around because it becomes a hard habit to break.

    The reason why it's inaccurate is because we have a lot of new technology out there in recent years, t5ho lights are far more intense than other fixture types with similar wattages. And as well, LEDs utilize little wattage so it goes out of the window with them as well.

    You could potentially use it as a very basic guideline, but I'd leave it on the shelf at that point.

    Now to Co2. Co2 is in the atmosphere, all around us, depending on your worldview this may be a good or bad thing, lol. Anyway, Co2 is present in low levels in the tank naturally. The idea behind injecting Co2 into a tank is if your lighting is requiring more co2 than the tank has in it naturally. Failure to meet the needs of the higher intensity lighting often results in an algae outbreak.

    And finally, ferts. Fertilizers can also be a simple thing in a low light intensity setup, the lower the light intensity, the less demand for fertilizers. Most tap water systems have a decent amount of micronutrients in them already, and the waste from fish via feeding (nitrogen and phosphorous) helps handle the bulk of the macronutrients.

    What does this all mean? It means if you go with a low intensity (low light) setup, you can essentially get away with growing plants (albeit slowly) without having to inject co2 or add fertilizers in routine.

    If/when you decide to go after faster or sometimes bolder (low light makes some plants leggy, while higher light makes them compact and bushier), at this point you need to figure out a fert dosing routine and co2 injection.

    There are some risks to running pressurized co2, but the disaster scenario is not the norm by any means, I've heard more horror stories about a tank leaking than I have about a co2 related issue that wasn't user error.

    As for your tank, I think we talked about this in another thread but if you want to keep it low light, a couple of cfl bulbs or dual bulb t8 would be plenty. Step it up to medium-ish intensity, which may or may not require fert/co2, go with a 2 bulb t5NO. High light would be a 2 bulb T5ho fixture. Keep in mind that it's MUCH easier to reduce light intensity than it is to increase it, so personally I like to go big and reduce as needed. Light reduction can be done by taking out one bulb, putting in a light diffusing material, or simply raising the fixture up off of the tank a few inches.
    Sorry for the long post but I hope this helps.
  11. OP

    melovefishValued MemberMember

    thanks for posting and all the info was great i wouldnt of got anywhere else !very helpful!!!
  12. RandomZoid

    RandomZoidValued MemberMember

    Thanks for all the good info Jeta, it was a good read.

    I knew this to be true before but to what degree? I apologize if this is slightly off topic.

    Right now I have a 29gallon tank (30wx12dx18h) with 2 T8s 5000k/8000k (17W each) and 2 CFLS 6500k (23W each). So that's 80W total but my most powerful is only a 23W. My question is, would buying a T5HO 2 Bulb (24W each) fixture be an upgrade even though it's only 48 watts total since it's a higher grade and my highest watt bulb is now 24?
  13. chevyguy8893

    chevyguy8893Well Known MemberMember

    I do believe that dual T5HO fixture would still be an upgrade if even if you ended up in the same high light category. On good T5HO fixtures (AquaticLife, Catalina, and Finnex for example) the reflectors are far better at directing the light into the tank creating a better PAR value at low areas. The bulbs are good for longer periods of time and more efficient.

    Now if the fixture in question was something cheap like odyssea where the bulbs may not have their own reflectors and the ballast is not running the fixture to what the specs say, it would not be an upgrade in my opinion. If you are getting nice growth that you are happy with then buying any T5HO fixture wouldn't really be needed at all.
  14. jetajockey

    jetajockeyFishlore VIPMember

    I would give the cheap t5hos a little more credit, they are not as good as the higher quality fixtures but they are still worlds better than most t8's. Here's some charts that give actual tested par data for various fixtures types and brands, it's not the be-all end all but it's a good start and can give people a basic understanding of the difference between the fixtures as well as the impact that fixture height plays in light intensity.
  15. chevyguy8893

    chevyguy8893Well Known MemberMember

    I stand corrected, I forgot that the odyssea and some other cheaper ones were on those graphs. I'm not sure I would ever trust the cheap ones seeing and hearing of some of the problems, but I guess that is possible with anything. That has been a helpful link a lot in the past for me, and many of hoppy's other threads.
  16. jetajockey

    jetajockeyFishlore VIPMember

    I've got a 3 bulb oddysea fixture that has been going strong for a year now. The bulbs were meh, but they did grow plants. I recently replaced them with some ge starcoats and now everything pearls heavily.

    Overall though my only complaint with the fixture is the bulbs are so-so, but for the price it's to be expected. Considering that it has 3x54w, moonlight LEDs, and a digital clock+timer to set individual bulb/moonlight on-off controls it's pretty hard to beat, price wise. (~$100-110 iirc)

    For the higher end fixture choices my favorite is catalina, I think its the most reasonably priced anyhow.
  17. JoannaB

    JoannaBWell Known MemberMember


    My tank is more and more a jungle. However, my fish seem to like it, and I do too, so all is well. I have low to medium light, use liquid frets and I do use Excel to supplement some CO2 mostly because before I did I used to have some beard algea and now I do not.

    I use the following fertilizers: Flourish Comprehensive, Phosphates, Nitrogen, and API Leaf Zone (for Potassium and iron).

    Recently I have been working especially on testing and adjusting the level of Phosphates in the hope of improving the health of my plants even further so that they shall hopefully outcompete the green spot algea that make it hard to see into my tank.

    This jungle tank is 8 months old, and I started out only with relatively few plants.

    Enjoy your new planted tank!
  18. psalm18.2

    psalm18.2Fishlore LegendMember

    I use DIY CO2 and my plants grow nicely. Simple to set up and maintain.