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FAQs on Carbon Dioxide and Planted Tanks 2

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

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

CO2 FW set up question      /RMF      8/31/16
I am setting up a freshwater planted tank, 120 gallons with CO2. CO2 includes tank, regulator, needle valve, bubble counter and reactor (DIY with maxi-jet, recirculating to venturi on pump). Lighting will be something along the lines of Finnex Planted + 24/7 fixtures.
I also will have it set up to a left over Digital Aquatics controller with Ph probe.
Is it better to use the controller/Ph probe (which, yes, will be calibrated before starting up) and run the CO2 dosing off a set Ph level (probably something in low 7s), or run the CO2 based off the lighting timer?
<I'd run the pH monitor AND a timer on it... operating/adding the CO2 during "lights on" hours or inside of these hours. Running CO2 when the lights are off can be tricky to deadly; driving pH down if buffering is off>
I haven't decided on plantings, but I have tended to lean towards medium/low light plants. I was hoping with the CO2 and sufficient lighting to maybe branch (pun intended) into some higher intensity plants.
Thanks for the help.
P.B in S.D.
<Oh, BobF in San Diego.... Will ask NealeM to resp. separately>
re: CO2 FW set up question      8/31/16

Unfortunately, running the solenoid off both timer and ph controller isn't an option. Sounds like running off light period and keeping an eye on PH is probably way to go?
<On during lights on then. BobF>
CO2 FW set up question /Neale       8/31/16

<Hello Paul,>
I am setting up a freshwater planted tank, 120 gallons with CO2. CO2 includes tank, regulator, needle valve, bubble counter and reactor (DIY with maxi-jet, recirculating to venturi on pump). Lighting will be something along the lines of Finnex Planted + 24/7 fixtures.
I also will have it set up to a left over Digital Aquatics controller with Ph probe.
Is it better to use the controller/Ph probe (which, yes, will be calibrated before starting up) and run the CO2 dosing off a set Ph level (probably something in low 7s), or run the CO2 based off the lighting timer?
<I would say using the pH probe. If the pH isn't right, fish can die; if the CO2 doesn't match light intensity, you just have less the perfect plant growth. Because pH changes as photosynthesis rate changes, pH and light intensity should track each other. Specifically, when plants do more photosynthesis (because there's more light) the pH goes up as dissolved CO2 (an acid) is removed from the water. Your pH meter should detect that and add extra CO2 as required.>
I haven't decided on plantings, but I have tended to lean towards medium/low light plants.
<In which case CO2 might not be needed. Overdoing CO2 when the plants aren't growing fast enough can cause a variety of problems. CO2 isn't needed at all for low-light (= slow growing) plants such as Anubias, Java ferns and Java moss.>
I was hoping with the CO2 and sufficient lighting to maybe branch (pun intended) into some higher intensity plants.
<Understood. Just ramming in a few high light intensity plants into a tank with low light plants doesn't always work though. Things like Anubias tend to get covered with algae unless positioned in relatively deep shade, and fast-growing plants will overwhelm slower growing plants if positioned in brightly lit areas. Some careful planning will be required here! There are various plant-specific forums on the web, such as ukaps.org, and I'd run your ideas past those folks before spending too much money or time on your project.>
Thanks for the help.
P.B in S.D.
<Welcome, Neale.>

dIy C02 SYSTEM   12/10/13
Hello wwm crew,
I am considering setting up a minor diy co2 system for my 125 gallon Planted tank.
<Mmm, one this size... and for what's invested, can be done... I'd go with a commercial rig>
The plants are currently anubias, Lots of Giant Val, java fern, java moss and an onion plant(generic name as the real one escapes
<Likely Crinum>
 Current stock is a 10 inch jack Dempsey, 2 Senegal bichirs, 12 giant Danios, 2 BN Plecs.
Filtration is 2 55/75 Aqueon power filters that documentation claims move 400g an hour. ( I realize that's at optimum performance). one on each end  of the 6 ft tank.  I also use flourish tabs approximately 5 tablets a month stuck by the base of the plant clusters. The tanks get 12-13 hours of  light a day.
I do not want anything to crazy in the co2 system was going to put a  single two liter with a sugar and yeast mixture at each end of the tank with the hose placed in the intake of that ends filter. My plants already grow ok just a little slower than I would like. I want the Val to spread faster as the bichirs love to weave through it and the more plants there are the Dempsey's plant tearing gets spread out more) I figured some co2 is better than none and may speed up growth. (also Have a minor algae problem on my rocks I was hoping this would help alleviate...only on my slate not on the glass at all)
My concern is that my tank does have a fair bit of surface movement from the two filters ( I do not want to loose
 this as it seems to be the primary entertainment of my Danios. they take turns forcing each other out of the current then swimming in it).
Also that my filters are self priming so if I feed the hose from the co2 into my intake it may proceed too siphon out the yeast mixtures.
I have also read about DiY systems nuking the oxygen out of tanks at  night which worries me a bit.
any advice or suggestion on this would be appreciated.
<Not to worry... Hopefully the sort, size generator, delivery system will  grant you some positive, appreciable plant growth... It is very doubtful it  can/will cause trouble. Bob Fenner>
Re: dIy C02 SYSTEM   12/10/13

I was worried about losing the current from the filters if I had to put in a diffuser to knock down surface agitation in order to not lose co2.
<Ehh! Some of this, some of that>
 My understanding is that surface agitation oxygenates the water and releases the c02.
<To some degree>

With me adding as little as I am I was worried the diffuser would be a necessity to not loose what little co2 I am trying to add.
thank you for the quick response.
<Welcome. BobF>

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.>

Large Planted Tank with CO2 9/19/10
I have started a 150 gallon planted freshwater tank and have a previous CO2 system I would like to add. My dilemma is 1) how do I measure how much CO2 I need for such a large tank? 2) I have a small ceramic glass diffuser from ADA that is about 1" diameter. It says it is for up to 20 gallons which is too small for my tank. What do I need to use as a diffuser for such a large size tank? I have upgraded to a used 0.6 kg CO2 tank (please see picture) and had it modified to attach to a simple CO2 system bought in a local pet store. I have a glass bubble counter to suction to the outside of the tank and a glass CO2 reader which shows yellow, green, or blue depending on how much is in the water. Should I just put the diffuser in there under the output tubes and see what the CO2 reader says in a day or two? I have attached pics of when It was hooked up to my 20 gallon quarantine tank I was using for plants. I have invested too much money in this already and am not really looking to add to it if I don't absolutely have to. Is there any way I can use this system in my large tank?
Thank you all!
<Lisa, having seen photos of your tank, I'm almost 100% sure that CO2 will make no difference at all. Can I strongly urge you to focus on [a] light intensity and [b] choosing the right plants for your ambient lighting levels, water chemistry, water temperature, and water current. I have an article about all of this coming in the next WWM Digital magazine which should be up in the next week. But in brief, there are two ways to decide how much CO2 to add. The first is trial-and-error. Assuming intense lighting, if you add CO2 at the tiniest amount you can in bubbles/second and wait for an hour, you should see "pearling" of oxygen bubbles on some plants. If not, add a tiny bit more. Repeat as required, all the time checking that [a] the fish don't look stressed and [b] there isn't a wild pH swing (there will be a slight pH decrease as you add CO2, but if it goes from 8 to 6 that's too much!). This approach is hit-and-miss and not terribly safe. The better approach is to use a CO2 test kit to measure the dissolved CO2. This should be between 10 and 20 mg/l. Add sufficient CO2 for a concentration of 10 mg/l, wait a couple of weeks, and if plant growth still isn't as good as you'd like, increase to 15 mg/l, and then a couple weeks later to 20 mg/l if needs be. Again, make sure the fish stay happy.
Above 25 mg/l CO2 will quickly kill your fish; in fact using CO2 is quite a good way to euthanise fish! So be very careful. There is a relationship between pH and CO2 concentration assuming you know the carbonate (not general!) hardness, so you can use a pH test kit to measure CO2 concentration. The formula is 3 x carbonate hardness (in degrees KH) x10(7-pH); thus if carbonate hardness is 5 degrees KH and the pH is 7.6, then the amount of carbon dioxide in the water will be 3.78 mg/l. If you're maths-phobic, then using a CO2 test kit will be safer. With all this said, your aquarium doesn't have enough lighting for CO2 to make much difference either way. You'd get far better results concentrating on plants adapted to relatively low light levels. These will find the CO2 produced by your fish and the filter more than enough, and even more so if you added a proper substrate, since microbes in the gravel and sand produce CO2 as well. Anubias, Java fern, Cryptocoryne wendtii, Vallisneria spiralis, hybrid Aponogeton, floating Indian fern, Amazon Frogbit -- all these should do fine in an aquarium with 1-2 watts/gallon, without the need for CO2. There is a VERY COMMON misconception in the hobby that CO2 is the thing that makes or breaks plant growth in aquaria. To some degree, the people selling CO2 appliances foster this idea. But it is COMPLETELY WRONG. While CO2 can make good planted tanks even better, it won't turn around a poor or mediocre one. It's a bolt-on goody for already successful systems. Cheers, Neale.>

water chemistry, FW... as relates to fish lvstk. sel. and planted system CO2 maint. 7/6/10
Dear Crew,
Thank you for the assistance that you provide us fellow hobbyists.
<Kind of you to say so.>
My question is related to water chemistry. I am currently in the process of setting up a 29 gallon freshwater planted tank. I have tested my tap water in the hope of determining the most appropriate water for various moderate to high light plants for my community tank. The tank will probably house Nerite snails, cherry shrimp, a couple Otocinclus and a school of tetras, probably Rummynose or cardinals though I understand cardinals don't like a lot of light ( 2 62 watt T5HO's).
<Okay. Well, for this mix you're after soft water. Cardinals require warmer water than Otocinclus, so they're poor companions. Yes, Cardinals are "photophobic" which is why they always look so terrified in Amano-style tanks! Fish school tightly when scared, and if you've ever seen a photo of an aquarium where the tetras are all bunched up, it's because they're frightened. One of the reasons I'm not a huge Amano fan is precisely this, that the need to create an aquarium that looks good in photographs trumps the needs of the fish. Stream-dwelling fish like Danios would be better for a tank like yours. Danios do well in the cooler conditions Otocinclus and Cherry shrimps desire, and don't mind open water at all. You aren't limited to Zebra Danios by any means, and with a bit of effort you should be able to find Glowlight Danios, Leopard Danios, Pearl Danios, and others. Minnows might work well too, both White Cloud Mountain Minnows and Vietnamese Cardinal Minnows are brightly coloured and thrive in relatively cool, bright conditions.>
My question is in regard to my tap water. I live in Arizona and my home has a water filter in the garage that is attached to all water coming into the house. The only thing that I know about this filtration system is that it has a prefilter and the water is filtered through carbon. I used API test kit for KH and GH. The tap water measures 6 drops for KH and I stopped trying after 30 drops for GH.
<Liquid rock. Perfect for livebearers; terrible for tetras. Your Cardinals would be dead within a year, likely 6 months, in such conditions.>
I then mixed the tap water 50/50 with RO water purchased from the local Wal-Mart Culligan system and the mix resulted in GH 14 and KH 4.
<This is moderately hard water; too hard for Cardinals in the long term, but fine for Danios and Livebearers, as well as the hardier Barbs and most Rainbowfish.>
I am afraid to use this mix as I was planning on using CO2 DIY and don't want the pH to crash due to the unstable KH of the mixed water.
<You will have to dose the CO2 carefully depending on the carbonate hardness. If you don't understand the relationship between pH, KH and the required CO2 concentration -- READ before even thinking about proceeding.
Please start here, with our friends over at The Krib:
I cannot stress too strongly how much easier CO2 is if you use a semi- or fully-automatic dosing system.>
Please advise my on how this carbon filtration has affected my tap water
<Filtering through carbon has no real impact on water chemistry at all; it removes some toxins, but that's about it.>
and if you think it would be wise to use straight tap with such a high level of GH and low level of KH.
<If you choose hard water fish like Guppies, sure. There are numerous plants that love hard water, and these usually don't need CO2 since they use bicarbonate in the hardness as their carbon source. Vallisneria and Elodea are two classic examples.>
The pH of the tap measured 7.4 and was the same with the 50/50 mix.
Thank you,
<Cheers, Neale.>

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