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FAQs on Carbon Dioxide and Planted Tanks: Sources

Related Articles:  Carbon dioxide and the planted freshwater aquarium by Neale Monks, CO2 Canopies

Related FAQs: CO2 & Planted Tanks 1CO2 & Planted Tanks 2, CO2 Canopies& FAQs on CO2 Planted Tanks: Rationale/Use, Yeast-Bottle Types, Compressed Gas Types, Control/Delivery, Measure, Dangers,

Mmm, the planet in general (CO2 is quite water soluble), foods, aerobic respiration; you, pets et al., carbonates in the water.

Planted tank filtration/co2 equilibrium? 4/14/2011
Hello WWM crew!
Hope you guys/gals are doing great and all is going well. As for myself, I'm in search of a new adventure, in aquaria of course, which brings me back to writing to you for a few quick answers if you could.
I am planning on setting up a 55 gal. moderately planted tank with no co2. I have tried a couple plants here and there with my fish tanks over the years and they never seems to work out, even the so stated low light, low maintenance, hardy plants. This time, after viewing through many Amano tanks, got my blood pumping once again'¦
<Oh noes!>
The setup will consist of: 55 gal. tank, T5HO 216 watts light (three 6500k bulbs and one 650nM bulb), approximately 3 inch layer of eco-complete, a Marineland Emperor 400 HOB filter, and a small in-tank powerhead with an attached sponge/ceramic noodle canister. So far so good?
<Sure. But do of course remember that the more splashing, the more CO2 is driven off. That's why HOB filters aren't a good choice for these sorts of tanks, though they have been used successfully, I have no doubt.>
My question is, from research, it seems that as though the HOB filter is a bad idea, due to surface agitation driving off the limited supply of co2 in the water.
Now reading at various info sources, this is true in the case of a co2 injected tank, but with a non injected tank, surface agitation is desirable?
<Don't see the logic here. The agitation at the surface increases the surface area of the water, and therefore CO2 will diffuse from the site of high concentration (the water) to low concentration (the air). Whenever you add CO2 to the tank, what you're doing is trying to exceed that diffusion rate by some carefully controlled amount, so an optimal CO2 concentration is maintained in the water. In almost all cases, plain vanilla aquaria have less CO2 in the water than is optimal, so plant growth can be limited by that -- assuming other factors, particularly light, are optimal. Nonetheless, light is FAR more often the limiting factor holding back plant growth in aquaria, not CO2, which is why most people find improving light increases their success with plants, whereas adding CO2 is the "icing on the cake" once you've already optimised lighting.>
Reason being is that the limited supply of co2 in the tank will be consumed rather quickly by the plants, and just like oxygen, co2 from the atmosphere will be infused into the water, though at low amounts, until an equilibrium is reached?
<There certainly is diffusion of CO2 between air and water, though the direction will depend upon which contains the most. But diffusion will have hardly any impact at all below the top millimetre, if that. Below that depth, it's circulation of water around the tank by your pumps that keeps CO2 moving around. Yes, if your plants are photosynthesising fast they will pull the concentration of CO2 in the water down towards zero, and yes, that'll cause diffusion of CO2 from the air into the water. But the rate that happens is slow, and in practical terms, plant growth will usually be held back through lack of CO2 because the supply of CO2 from the air via diffusion just isn't fast enough. Hence adding CO2 to aquaria where very fast plant growth rates are desired.>
Is this true and should it be followed? Basically circulation and surface agitation desirable in a non co2 injected planted tank?
<Agitation is, broadly, undesirable, at least if you want to minimise the cost of adding CO2. Of course if you can supply CO2 faster than agitation allows it to diffuse out into the air, then that isn't a problem.>
Or should I be looking for an external canister filter where I can put the return underneath the water line?
<This is the standard approach.>
I doubt it will turn into an Amano creation, but we'll see where it leads me... Tank will be mostly plants with very little live stock, but I refuse to have a tank without a Pleco of some sort.. Love those catfishes and was thinking of an Ancistrus of some sort for this tank.
<Can work in planted tanks. But do look at things like Parotocinclus jumbo and Hypancistrus sp. L260 as potential alternatives. Obviously the more carnivorous genera, such as Hypancistrus, are better bets than the more dedicated herbivores, such as Panaque.>
Thanks greatly for your time and effort. Hope everybody has a great year!
<And today is, in fact, Khmer New Year, I'm told.>
<Cheers, Neale.>

Re: Adding light, plants, and kubotai loaches to stable 55gal freshwater community; Human-powered CO2 infusion system!   11/13/09
Hi Neale, and thanks again for the pointers.
<Happy to help.>
UPDATE. I did a lot more reading here and at The Krib (among many other places). I considered lots of CO2 options. I might still go with pressurized cylinders someday. I even tried simply exhaling into a powerhead venturi, but then I settled on an even better, VERY low-tech solution. It's a variation of something I got here at WWM:
CO2 SOURCE: human respiration (that would be ME)
CO2 RESERVOIR: 55 gal trash bag attached to air lineCO2 DELIVERY: airline attached to venturi input of Penguin powerhead Scrounging around the house, I found a water bottle, cut large slits in the sides, and taped the bottle securely inside one corner of the 55 gal bag with just the top sticking out. That way I can blow into the bag (via the bottle top) whenever I want. And when I'm done, I simply cap it. (Any tube and cork would do.) At night, a timer also turns on my second filter, a hang-on-the-back, bio-wheel model, Emperor 400,
- IT'S FREE. It uses redundant equipment (the UGF-ready powerhead I already have) and is effectively free. You don't even need special air line because I don't think human exhalation breaks down plastic like purer sources of CO2 would.
- IT'S SAFE and WORRY-FREE. This setup is very forgiving. If my CO2 system fails, my plants simply slow down. Nobody gets hurt. No end-of-tank dumping to carbonate my tank like a root beer-and-Pleco float. No regulator to fail. No 2-liter bottle to clog and explode. No valve to break and asphyxiate me while driving (or turn my tank into a missile). I don't even have to worry about turning it off at night, because human exhalant also carries plenty of oxygen.
- NO MESSY LIQUIDS. I don't have to keep a yeast culture (yeast creatures, fun as they are, are not as rewarding as fish or plants).
- IT'S NATURAL. I get a kick out of including as many biological cycles into my system as possible--that's a pure tinkerer's delight.
DISADVANTAGES (pretty obvious)
- REQUIRES DAILY ATTENTION. Breathe, baby, breathe! But this is easy if I just remember to breathe into the bag for a few minutes while I'm pleasantly watching the aquarium.
- THE BAG IS UGLY (but can be hidden behind or underneath the cabinet)
DOES IT WORK? Most definitely! Yes, it works great! One bag full can last all day (or maybe two days). I didn't measure the pH shift but my plants started pearling up right away. Some leaves give off a very fine stream of bubbles at regular intervals (mostly crypts, swords, and java fern, with some Egeria and Ceratophyllum). I never saw that before in my tank! Except for maybe a few minutes (or seconds) *immediately* after a large water change.
All the best to you and rest of the WWM Crew! --dc
<Sounds a fascinating way to approach this problem, and that it works is very good to know. You might consider taking some photos and writing a couple thousand words on what you do. This is precisely the sort of article I'd love to run (for money!) over at the Conscientious Aquarist side of the WWM empire. Cheers, Neale.>

Re: Adding light, plants, and kubotai loaches to stable 55gal freshwater community  11/15/09
Yep! your WWM article was part of my (recent) education on true aquatics.
Very helpful.
<Good to know this article helped. Hope the remainder of your plant choices are more successful. Cheers, Neale.>

Re: A host of things: substrates, water parameters, stocking options   8/22/09
Alright Neale,
Your response got me thinking about a lot of different options. I may go for the Amazonian set-up as planned, swapping out M. ramirezi for M. altispinosus.
<A good idea. Since these cichlids, plus many tetras and most South American catfish thrive in both soft and moderately hard water, it's easy to create an Amazonian set-up without the expense of creating soft water.
With moderately hard water, pH stability is easy to ensure, and your filter bacteria will operate optimally, since these prefer hard, basic water.>
I'm starting to be drawn more to doing either a hard water or low-salinity brackish set-up (around SG 1.003). Then, I can still take advantage of a live plant set-up, while using my area's water chemistry more easily, and also keeping some very interesting species. That all being said, I have a few more questions, based on our previous discussion, as well as other articles I've read on the WetWebMedia site:
1) The CO2/CO3 issue: I've read about hard water plants that can utilize carbonate salts as their carbon source rather than CO2. Would it still be beneficial to supplement these plants with CO2?
<Yes; while such plants can use carbonate, if given CO2, they photosynthesise that bit better. Equally, the removal of carbonate allows pH to change, creating variable pH conditions when day is compared to night. Note that in places like ponds and lakes, such pH changes happen and animals adapt to them, so in themselves, pH rises and falls on a daily, cyclical basis are not intrinsically lethal.>
It seems to me that adding carbon dioxide would simply use up the water's carbonate buffer reserve more quickly, making the desired hard water less hard. Thus, to add CO2 to any useful effect in an aquarium with high KH would unacceptably change water chemistry. Is that how it tends to work, or is it not that simple?
<It's complicated, but has been thoroughly worked out now. Do see here:
I'm not an expert on CO2 fertilisation -- have never used it -- but would direct you to those good folks at The Krib who really know about this stuff.>
2) I've got a few different ideas for stocking arrangements for fish for the hard water set-up, one of which I'd like to run by you: a school of *Melanotaenia *praecox, two Kribensis (probably female, to decrease territoriality and prevent breeding--desired for the time being), perhaps one other which I would carefully research/choose, and lastly, *Colomesus* asellus. That's the particularly question-mark fish of the group, of course. I'd really like to keep about three of them. I know that it is debated whether a puffer even as peaceful as this one should be kept with other fish, whether it would be a healthy fit in general. I read the article you wrote, "The Nice Puffer," and you offered a few words about this topic. I'm wondering if you can tell me a little bit more of your opinion on the matter.
<Will depend on the size of the tank: my SAPs are largely well behaved in a 180-litre system with rocks and floating plants to provide cover. In smaller tanks, your degree of success may well be less.>
With the Kribensis, my reasoning is that the SAP won't be as demanding of the caves as other puffers might be, and thus won't compete with the Kribensis, and that the cichlids can defend themselves against nipping.
<Have kept SAPs with a different Pelvicachromis species, P. taeniatus, and they worked pretty well except for the occasional nipped dorsal fin.>
I'm hoping the M. *praecox *are active and fast enough to evade harassment by the puffers?
<Might be, but again, will depend on the amount of swimming space. Some rainbowfish species tend to sit about in midwater rather than actively patrol the tank, so think about that when shopping. Big groups and strong water currents should tilt the odds in favour of the rainbows.>
Also, are there other fish that would fit into this arrangement well?
<Pretty much what's written in that article! Have subsequently found Ameca splendens works well with them, and by extension, you might consider other feisty Goodeids, such as Xenotoca eiseni.>
I don't know about the puffers. I'm really interested in having one of the interesting hardwater/brackish oddball groups for the variety they provide, and I'm very drawn to these SAPs.
<They are great fish. However, Carinotetraodon irrubesco is perhaps that bit easier to slot into community tanks, and with floating plants available, spends much time in the open and at the top of the tank, begging for food.>
Let me know what you think.
Once more, thanks for your help,
Joey E.
<Cheers, Neale.>

CO2 Website Recommendations   2/16/08 Hi, I just wanted to tell you about the setup I have. I have a 40 gallon display, tall tank with a 6.4 pH and good ammonia, nitrites, and nitrates, forgot the numbers, but I believe it was low, and I have very soft water. I have a whisper filter that pumps 100 gallons per hour, and in addition, I have 3 undergravel filters. I use glass gravel and I have some ornaments and hiding spaces for the fish. I have the bubble generator to supply oxygen for the fishes. In the tank, I have 3 live plants, planning on getting 2 more but not sure what types. I wanted to get a floating plant for the discus, what would you recommend? <Water sprite would be a good choice to try depending on your conditions.> I have 3 discus, and 10 cardinal tetras. I keep the temperature at 82 degrees. Is this overstocked or is it possible for me to add any more cardinal tetras, possibly 10 more, or is it too much? <Keep the nitrates under 20 ppm with water changes. Live plants will help with the nitrates depending on the lighting and general health of the plants. If you cannot keep the nitrates under this level then I would recommend not adding any additional fish.> I do 30 percent weekly water changes and feed them frozen bloodworms, brine shrimps, beef heart, occasionally, and flakes. I am also trying to build a carbon dioxide generator, as I saw online. However, there are so many different recipes for the reaction, which one would you go with? Do you recommend making one? Thanks so much for your help. < A good friend of mine runs a website called thekrib.com that discusses CO2 and the pros and cons of adding CO2. This is not a toy and can wipe out your entire tank if not used correctly. I recommend reading this website often and do not use CO2 until you know what you are getting into. If you do decided to go this route then it will help you build a CO2 unit with everything you will need.-Chuck>

Planted Tanks... Seltzer water for CO2, pots...   2/28/08 Thanks For Your Great Website, The Cream of the Crop ...... <Okay!> I am not new to the hobby, 20 years of Fresh Water Planted & Marine/Reef. Enjoy the hobby so much I build custom acrylic aquariums/sumps, complete set up in Garage to do so with all essentials needed for a professional result. <Neat!> (Police Officer as a Career) I recall as a child, a neighbor with a planted tank, would replace his evaporated water with Seltzer Water, Have You ever heard of this? <Gosh... it's been years... but yes... for the, oh I see this below> I personally don't see the reason to add CO2 to any of my Planted Tanks (But a firm Believer of Iron Additives). <Agreed... carbon dioxide is readily available... from inside and outside tanks... readily soluble in water... generally not rate-limiting...> I have a RODI Unit that I use as an ATO, but Always pondered the thought of all the half full seltzer bottles I emptied into the sink. <? Maybe... smaller bottles, are they going too-flat for drinks? Can/could be poured in your tanks> Second Question.. any benefit in leaving potted plants in the pots when planting? Take Care.. Matt <Mmm, perhaps to save a bit of mess... some are made to fall apart/decompose over time... By and large I remove these pots myself ahead of planting. Cheers, Bob Fenner>

Aquatic plants  5/17/07 hello again. <Hello> I have a new question about Aquatic Plants. I'm thinking about starting a Garden and seeing some of the pictures online I was and still am completely amazed by it all. However, I still have a few questions.... the first question I have is about filtration. Is it possible that when I set up the tank and the plants that all I could use would be a bag of active charcoals to help put co2 into the water system for the plants to feed off of? <Maybe... adding carbon will in some ways make it available... but gaseous introduction is the best, surest way of provision> I have looked on the site... but there isn't a sections for water garden plants for dummies so all the places I've looked have all these technical words that I really don't understand. could you help me out please? thanks, Paul <Do give the Krib (.com) a read as well as Dennerle and Tropica's sites... perhaps Takashi Amano's books, Pablo Tepoot's one volume on plants, planted systems... There is, indeed, much to know... and therefore good reason to invest ones time in study here. Bob Fenner>

Air pumps, aerating planted tanks  - 05/13/2006 I was reading in a book and it said that keeping air pumps on during the day is not really a good idea... if you have plants. <Can be detrimental... as this "drives out" Carbon dioxide, adds oxygen...> It did not really give a reason but it said that since photosynthesis stops during the night hours, <Actually... the dark reaction/s of photosynthesis occur during non-lighted periods...> and everything in the tank gives off carbon dioxide, that it is a good idea to have an air pump / air stone running at night. Should I leave air running all day or do what the book suggests. Thank You <I would likely leave all running continuously... much more to this "story" then stated here... likely other factors are much more important to your overall plant growth, health... Too much chance, possibility of trouble with leaving gear off... Bob Fenner>

Re: new 72-gallon tank setup Hi Ronni, <Hello again Paul!> This is Paul writing to you from Toronto, Canada again.  We last talked about a month ago while I was in the process of setting up my 72 gallon tank. <Yep, I remember> I finally got my tank running and everything looks like it's going well.  I have a total of 19 fishes and several plants.  Even though my plants are doing okay, I would like to inject some CO2.  There is a product from Germany called "Carbo Plus" which generates CO2 by electrolysis.  Have you heard of such product?  What is your opinion of it?  Do you know of anyone that have used this product and are fully satisfied?  The apparatus is quite costly and I would like to get some feedback before investing in it. <Honestly, I've never heard of it so don't know whether it works well or not but I would recommend asking about it at http://wetwebfotos.com/talk/ as someone there is bound to have tried it.> Thanks and take care. Paul <Sorry I couldn't be of more help! Ronni>

Carbo Plus for Co2 Hi Bob, I have my 72 gallon setup running for about a month now with several plants and about 20 fish.  I would like to add co2 to give my plants a boost by injecting co2.  There are several methods out there and I have come across a German product called "Carbo Plus".  Have you had any experience with this product??  Or do you know of anyone who has used this product and been very successful.  The product sounds too good to be true.  Since it's an expensive investment, I would like to get some feedback first. Thanks for your time to response. Paul <Have seen this product in magazines and at the international tradeshow, the InterZoo (in Germany). The science is sound, but I still prefer CO2 injection... w/ or w/o a meter in concert. Bob Fenner>

Construction of a CO2 Canopy for Plant Tanks <Interesting concept. Have you considered submitting this work for pet-fish magazine subscription? Please do. Here is the name, email address of a friend, Sue Steele, who acts as the Managing Editor of Freshwater and Marine Aquarium Magazine in Los Angeles: famamag@aol.com. You may want to re-do your drawings (for clarity and publication). Will post your name, article on the Plants Subweb of WetWebMedia.com with your name and permission. Bob Fenner>

Construction of a CO2 Canopy for Plant Tanks Dear Bob, <Lalith> Thank you very much for replying my mail. I am so happy that you considered it as a good project. Many thanks for agreeing to publish my article in your web site. I will also submit it to Freshwater and Marine Aquarium Magazine with better drawings. In the meantime I will contact your friend Sue Steele with the present document. Once I redo it I will forward it to you. I very much appreciate your kindness in giving your support to my little work. <A pleasure my friend. It will be well-received and stir people on to experimentation, application, considering their possibilities. Could there be anything better? Bob Fenner> Lalith

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