# CO2 Injection equipment



## Manwithnofish (Mar 12, 2008)

I give up so where can I find a discussion about CO2 Injection equipment. What's needed, where to purchase, etc.? Is the pH controller a luxury or a necessity?


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## hoppycalif (Apr 7, 2005)

http://www.bestaquariumregulator.com/index.htm is one good place to look. The pH controller is unnecessary, but some people like to use it.


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## Manwithnofish (Mar 12, 2008)

Crap, I just typed in a long question and the site refreshed on me and lost my box.


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## Manwithnofish (Mar 12, 2008)

What's the purpose of the two gages? One regulator, has a fixed "working" pressure of 1.5 bars. What does that mean?

Do all tanks w/regulators have a valve on top of tank to open and close or does the regulator do that? I've seen some pictures with the hand valve like an out door water faucet and some without.


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## hoppycalif (Apr 7, 2005)

All CO2 tanks (paint ball tanks not included) have a hand valve on top that shuts off the tank. A regulator needs two gages - one to show the incoming pressure, which tells you when the tank starts running out of liquid CO2, and an output pressure gage to tell you what the set pressure of the regulator is. A "bar" is one atmosphere, or about 15 psi. 20 psi is about the lowest pressure you can set most CO2 regulators to and get consistent results. Some regulators are pre-set to that pressure and are difficult to reset to another pressure. Others have a knob that lets you set the pressure easily. JBJ is a preset one, and Milwaukee is one with a setting knob.


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## Manwithnofish (Mar 12, 2008)

> Some regulators are pre-set to that pressure and are difficult to reset to another pressure.


If the output pressure is fixed, what is the function of the needle valve? Do you want to reduce the pressure from 20 psi to a much lower flow rate?


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## mulita (Jul 31, 2007)

Manwithnofish said:


> If the output pressure is fixed, what is the function of the needle valve? Do you want to reduce the pressure from 20 psi to a much lower flow rate?


The pressure is fixed but the needle valve is to control the flow of gas, normally measure in bubbles rate per second, that the reason for bubble counter


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## Jareardy (Feb 14, 2008)

so yes the needle valve is to reduce the outflow of the gas to a minuscule amount.


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## AaronT (Apr 26, 2004)

You need:

1) A dual gauge regulator. One gauge tells you how much gas is left in the tank and the other reduces the pressure to a workable pressure, usually down from 800-1,000 psi to 10-20psi.

2) A needle valve. The needle valve reduces the pressure even more to a *very* slow rate. Do not try to use the regulator to achieve this.

3) A bubble counter to measure how much CO2 is exiting the tank.

4) Some sort of diffusion device. It can be as simple as feeding the end of the airline into the intake of the filter.

5) A CO2 tank.

Optional Items:

1) A solenoid. A solenoid allows the flow of the CO2 to be turned off electronically usually with a household appliance timer. This is a good investment as it will save CO2 during the evening when it is not needed by the plants.

2) A pH controller. Many people swear by them, but I've never been a big fan. They can be skewed too easily by anything that may be buffering the water.


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## Manwithnofish (Mar 12, 2008)

> Optional Items:
> 
> 1) A solenoid. A solenoid allows the flow of the CO2 to be turned off electronically usually with a household appliance timer. This is a good investment as it will save CO2 during the evening when it is not needed by the plants.
> 
> 2) A pH controller. Many people swear by them, but I've never been a big fan. They can be skewed too easily by anything that may be buffering the water.


So, the solenoid (which is an electronic switch) can be turned on and off either by a timer or by a controller like the pH device (correct)?

And if I choose to use the timer, I simply plug the solenoid into the timer. When it's on it on and when it's off it's off. But if I choose to control the solenoid by the pH controller, I plug the solenoid into what, the pH device or how do those two devices interface? I have seen some referrence to a BNC connector. Is that how the solenoid and pH device have to connect?


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## hoppycalif (Apr 7, 2005)

AaronT said:


> You need:
> 
> 1) A dual gauge regulator. One gauge tells you how much gas is left in the tank and the other reduces the pressure to a workable pressure, usually down from 800-1,000 psi to 10-20psi.
> 
> ...


A minor error: the needle valve isn't there to reduce the pressure. It just restricts the flow of CO2 through it. The pressure downstream of the needle valve will be the total of the pressure losses in the CO2 tubing to the tank, the check valve, the bubble counter, the diffuser and the actual pressure of the water in the tank - the height of water above the diffuser.


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## mott (Aug 6, 2006)

I would like to suggest My friends co2 site.
They make top quality reg's
http://www.sumoregulator.com/


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## AaronT (Apr 26, 2004)

hoppycalif said:


> A minor error: the needle valve isn't there to reduce the pressure. It just restricts the flow of CO2 through it. The pressure downstream of the needle valve will be the total of the pressure losses in the CO2 tubing to the tank, the check valve, the bubble counter, the diffuser and the actual pressure of the water in the tank - the height of water above the diffuser.


Good catch. 



> So, the solenoid (which is an electronic switch) can be turned on and off either by a timer or by a controller like the pH device (correct)?
> 
> And if I choose to use the timer, I simply plug the solenoid into the timer. When it's on it on and when it's off it's off. But if I choose to control the solenoid by the pH controller, I plug the solenoid into what, the pH device or how do those two devices interface? I have seen some referrence to a BNC connector. Is that how the solenoid and pH device have to connect?


Yes, you are correct. The solenoid is either turned off by the timer or the pH controller if there is one. It just plugs directly into either one.


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## AndrewB (Jul 7, 2006)

My lfs recommended to me to turn the CO2 on 30 mins before I turn the lights on and, then turn off the CO2 30 mins before lights out to limit the pH fluctuations


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## hoppycalif (Apr 7, 2005)

AndrewB said:


> My lfs recommended to me to turn the CO2 on 30 mins before I turn the lights on and, then turn off the CO2 30 mins before lights out to limit the pH fluctuations


That is a good idea, but it isn't to limit pH fluctuations. The early shutdown is to limit the exposure of the fish to high CO2 levels that aren't useful to the plants. And, the early start of CO2 is to build up the concentration so when the lights come on the CO2 concentration is in the right ballpark for good plant growth. When you use CO2 you accept that there will be pH fluctuations, but those are not a problem. It is only when the pH changes are due to additions or removal of dissolved salts that they can be harmful.


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## AndrewB (Jul 7, 2006)

Ah that makes sense!
Thanks Hoppy.


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## Manwithnofish (Mar 12, 2008)

> When you use CO2 you accept that there will be pH fluctuations


But isn't that the purpose of the pH controller? To turn the CO2 on and off in order to maintain a stead pH level? Based on "the" kH/pH/CO2 table, I have determined that I should have the correct amount of CO2 if I try to maintain a pH level of 7.0.


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## AaronT (Apr 26, 2004)

Manwithnofish said:


> But isn't that the purpose of the pH controller? To turn the CO2 on and off in order to maintain a stead pH level? Based on "the" kH/pH/CO2 table, I have determined that I should have the correct amount of CO2 if I try to maintain a pH level of 7.0.


For me this still has its flaws. The controller is set based on the KH of your water. The KH of tap water can fluctuate a degree or so sometimes. Also, putting things like driftwood or certain stones in the tank can buffer the KH. There are just too many variables for it to make sense to me.

The pH swings are not harmful as hoppy said. I've had many tanks with a KH of 2 or less with 24/7 CO2 and super healthy, even spawning, fish.


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## hoppycalif (Apr 7, 2005)

In my opinion the obsessing over pH began because it is easy to measure pH with relative accuracy, but it is much harder to measure the total dissolved solids in the water. But, the fish react to the TDS, not to the pH. If you monitor pH, and don't use CO2 in the water, you have an easy, if crude way to monitor TDS, and a big change in pH then means a big change in TDS, which is harmful to the fish.

I hope that makes sense.


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## Manwithnofish (Mar 12, 2008)

> I hope that makes sense.


 Yeah, you kind of lost me on this one. I'm not debating how logical it might or might not be to monitor pH, kH or TDS. I'm just trying to confirm that I understand the hardware and how it works.


> The controller is set based on the KH of your water.


 I thought the pH controller had a probe in the water monitoring pH which the controller then based on whatever pH you selected as the target or range, would simply turn on / off the CO2 via the solenoid? So, if one were to decide to strive for a stead level pH within the tank, the hardware will strive to maintain that value? Whether or not this is a good strategy that makes sense is a good discussion (that I appreciate), but I need to just make sure I understand how it works first.


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## AaronT (Apr 26, 2004)

Manwithnofish said:


> I thought the pH controller had a probe in the water monitoring pH which the controller then based on whatever pH you selected as the target or range, would simply turn on / off the CO2 via the solenoid? So, if one were to decide to strive for a stead level pH within the tank, the hardware will strive to maintain that value? Whether or not this is a good strategy that makes sense is a good discussion (that I appreciate), but I need to just make sure I understand how it works first.


Yes, that's how it works. The pH you set it to is based on the KH of the water though. If the KH changes it may buffer the water too much or too little.


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## Manwithnofish (Mar 12, 2008)

My kH isn't fluxuating. My pH and CO2 however is. kH doesn't necessary have to change when pH and CO2 levels change does it?


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## TWood (Dec 9, 2004)

By definition KH is the measure of the ability of the water to resist a change in pH. High KH means lots of CO2 has minimal effect on pH, low KH means lots of CO2 will move the pH rapidly. My tapwater has a KH of 16, so it's possible to stress the fish with too much CO2 and never see the pH move much. But if I dilute it so the KH is around 3, I can add relatively little CO2 and move the pH a lot. For reasons that probably make sense business-wise, at a KH of around 3 the typical hobbyist pH test kits are in the range where they give readings that are close enough.

A pH controller is a waste of money because it is measuring the wrong parameter. The amount of CO2 in the water is what we need to know. pH is used indirectly to get there, but it has its flaws as a proxy measurement for CO2. The BNC connector would be used to connect the probe to the controller.

TW


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## AaronT (Apr 26, 2004)

Manwithnofish said:


> My kH isn't fluxuating. My pH and CO2 however is. kH doesn't necessary have to change when pH and CO2 levels change does it?


That's my fear with using a controller. The whole idea is based on the KH *not* fluctuating. My fear is that it can fluctuate, whether it be from some object buffering the water somehow or if the tap water changes.


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## TWood (Dec 9, 2004)

The real problem with a pH controller is that it is counter-productive. With a KH around 3-5, you WANT the pH to fluctuate as CO2 is added to the water during the day, and then outgasses at night. Set the pH low and there's too much CO2 in the water at night. Set the pH higher and there's too little CO2 during the day.


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## Manwithnofish (Mar 12, 2008)

Ok. I've cancelled my order for all the equipment and I'll start over. Don't need pH controller, save $80.00 (this is good).

Mott said


> I would like to suggest My friends co2 site.
> They make top quality reg's
> http://www.sumoregulator.com/


 This site has no contact phone number or an online order form. Hummm

My kH has been pretty consistently measuring at 6 or 7. My gH has been running around 14. So, if I control the regulator / CO2 flow with a timer, I should be able to add enough CO2 to accomplish what I want with the plants and not create a dangerous environment with the other parameters? My pH out of the tap (well water) is about 7.4. After being in my aquarium it runs up to about 8.0 or 8.2. I am hoping to kill two birds with one stone. CO2 increase feeds plants and brings pH down to 7.2 or something better than where it is. Is this a reasonable objective?


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## TWood (Dec 9, 2004)

It doesn't matter where the pH ends up. That's not an important number, unless it's WAY off into the low deadly range. The amount of CO2 in the water is the important number, and even then you can approximate it and be close enough. Adding CO2 to get a target pH is backwards. The pH is the result of adding a certain amount of CO2. Add enough CO2 to grow the plants and not hurt the fish. Whatever pH that ends up creating is whatever it is.


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## Manwithnofish (Mar 12, 2008)

If pH doesn't matter and I don't care what it is.....why do I have two test kit bottles to measure it and why do I measure it? I mean if it was in the deadly range, I'd wake up one morning and all my fish would be swimming with their feet pointing straight up. Am I missing something?


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## Sandman (Mar 5, 2008)

This is advice I recieved from a very experienced aquatic plant person. I thought I would pass it along since it may be useful to others.



> A PH monitir is useful only if you're going to be pushing the limits, say 35-40ppm of CO2. Otherwise 15-30ppm does not require the accuracy of a PH controller. If you choose to use one, you "must" clean the probe regularly as a false PH reading will turn the CO2 on when it shouldn't be on. It's another point of failure in my opinion, I retired mine many years ago and haven't regretted it.
> 
> You'll find that erogating CO2 24/7 produces the best results and stability in PH. Turning CO2 off at night can cause some large swings in PH which most plant people will advise you against.
> 
> ...


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## TWood (Dec 9, 2004)

Manwithnofish said:


> If pH doesn't matter and I don't care what it is.....why do I have two test kit bottles to measure it and why do I measure it?


Marketing!


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## hoppycalif (Apr 7, 2005)

If you are willing to limit the amount of CO2 you have in the water to the 15-20 ppm range I agree that it makes little sense to turn it off at night. Doing so just reduces the frequency of refilling the CO2 tank. And, that concentration of CO2 in the water doesn't seem to harm any fish at all. Edward promotes the idea of using CO2 in that range as the optimum concentration.

But, if you want to use really high light intensity, and drive the plants to grow as fast as that light lets them grow, then you need to provide more CO2 in the water, in my opinion. That is where the 30 ppm figure comes from. The problem is that there is no economical way to measure the CO2 in the water that prevents you from having 45 ppm when you think you have 30 ppm (or it could be 25 ppm when you think you have 30 ppm). So, shooting for 30 ppm, which may be tolerable for fish 24 hours a day may make you hit 45 ppm which almost certainly isn't tolerable for 24 hours a day. That is why I think using a solenoid valve to shut off the CO2 at night is a good idea - the fish need a respite from the CO2.

A pH controller doesn't make the ppm of CO2 any more accurate. That is because the amount of CO2 in the water, for a given KH, is proportional to 1 divided by 10 to the pH power. A small error in measuring pH gives a big error in ppm of CO2. And, pH controllers are not accurate enough to get around that problem. An error of .1 in pH gives an error of 25% in ppm of CO2, and most controllers are no more accurate than that.

In addition, because aquarium water is never the ideal water that the CO2/KH/pH equation works for, you need to measure the actual ppm of CO2 in the water using something like a drop checker. Then the pH controller can be used to hold the water to that ppm instead of relying on the needle valve to hold a constant bubble rate. But, unless you use a quality pH probe to measure the pH of the drop checker water, instead of relying on the color of the water, you are limited by your ability to judge that color.


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## Sandman (Mar 5, 2008)

Hoppy,
So it sounds like you basically agree with the advice I was given. Unless you're pushing the limits on the amount of CO2 going into your tank, leaving the CO2 on 24/7 is fine. Yes, it will use more CO2 but it also eliminates the need for a solenoid (and electricity) and should keep the PH at a more constant level...


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## Manwithnofish (Mar 12, 2008)

Going back to TWOOD post #23.


> High KH means lots of CO2 has minimal effect on pH, low KH means lots of CO2 will move the pH rapidly. My tapwater has a KH of 16, so it's possible to stress the fish with too much CO2 and never see the pH move much. But if I dilute it so the KH is around 3, I can add relatively little CO2 and move the pH a lot.


Isn't this a contradicting statement from the information below?



> From Chuck's Planted Aquarium page:
> Myth: A Low KH results in a larger pH swing when adding CO2.
> Many people are under the mistaken impression that a low KH results in large pH swings when adding CO2, while raising the KH will result in smaller pH swings. This is not the case. The KH will move the start and end pH values, but the pH swing will be the same for a given level of CO2. You can see this in the chart below, or using the calculation:
> 
> ...


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## hoppycalif (Apr 7, 2005)

Sandman, yes I agree that keeping the CO2 on 24/7 works fine, if you keep the ppm of CO2 around 15-20. (But, understand that the limitations on our ability to measure ppm of CO2 in tank water mean the actual ppm of CO2 when we have "15-20ppm" may be about 10 to 30ppm.) I tried that for several months on my tank, but quit when I got tired of fighting BBA, which I hate.

One more "data point": Recently Tom Barr obtained an accurate CO2 tester - $2000 price range - and was disappointed to learn that he had less CO2 in his tanks than he had been sure he had using the other methods available for us to measure CO2. This is another good reason to shoot for high CO2, but watch for excessive fish distress.

If you look at percent changes in pH, high KH leads to smaller pH changes with a given amount of CO2, and low KH leads to higher pH changes. But, if you look at actual change in pH - say a 1.0 change - then KH has no effect on the change a given amount of CO2 will cause. This is because with low KH you have low pH for any given amount of CO2, and with high KH you have high pH for that amount of CO2.

In my opinion, and as I recall from my very limited chemistry knowledge, "buffering" refers to a solutions ability to hold the same pH with additions of a substance that normally reduces or increases the pH. And, that "buffer" is normally a mix of a base and an acid, not just a base, as KH involves. (If this is garbled, it is only because of my very limited knowledge of chemistry.) So, it is a misuse of the term to say higher KH water "buffers" against the tendency of CO2 to decrease the pH of the water. (If I am correct in my understanding.)


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## captain_bu (Dec 13, 2007)

Manwithnofish said:


> Ok. I've cancelled my order for all the equipment and I'll start over. Don't need pH controller, save $80.00 (this is good).
> 
> http://www.sumoregulator.com/
> This site has no contact phone number or an online order form. Hummm


Sumo built me a regulator this week. It is being shipped today. There is no phone number on the site but there are email links for questions or orders. Sergio was quick to respond to my email and super helpful in answering all of my questions. They use excellent components. Search through some of the forums for problems people are having with CO2 and you will start to realize the importance of a good quality needle valve and a regulator that will hold a steady, adjustable output pressure. Following is a link to a primer that covers all of the various necessary and optional components of a CO2 system.

http://www.njagc.net/articles/co2.htm

Rex Grigg's site also has great info and pictures of how to set up and use a regulator.

Here is a picture of the regulator Sumo built for me. I had them integrate a JBJ bubble counter into it.


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## TWood (Dec 9, 2004)

hoppycalif said:


> So, it is a misuse of the term to say higher KH water "buffers" against the tendency of CO2 to decrease the pH of the water. (If I am correct in my understanding.)


Huh, well then I'm wrong in my understanding of what KH really is.


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## Manwithnofish (Mar 12, 2008)

My policy is simple. Never answer questions, just ask them. That way I can never be wrong.. Maybe one day I'll figure out what half of this stuff means. Anyway, thanks for the discussion. I am learning a lot. I'd never figure this out without the forums.


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## hoppycalif (Apr 7, 2005)

Manwithnofish said:


> My policy is simple. Never answer questions, just ask them. That way I can never be wrong.. Maybe one day I'll figure out what half of this stuff means. Anyway, thanks for the discussion. I am learning a lot. I'd never figure this out without the forums.


You just need to decide that you really enjoy egg on your face. After awhile it seems normal.


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## TWood (Dec 9, 2004)

I love the smell of eggs in the morning...

I'm not a mathematician, nor do I play one on TV, but isn't the pH scale logarithmic as it moves in either direction from the neutral at 7.0? Isn't a change from 8.6 to 7.6 a gazillion times bigger than a change from 7.6 to 6.6? That would explain the apparent contradiction with the charts.


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## Manwithnofish (Mar 12, 2008)

Well, I thought logs meant that there was a 10 fold difference between 6.0 and 7.0 and 10 fold difference between 7.0 and 8.0. So 8.0 would be 100 times greater than 6.0. I'm not sure if pH is on a log scale, but the amount of change between single units would be the same (I think). I know someone who knows someone who knows, but they won't talk to me because I don't know enough to understand them.


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## hoppycalif (Apr 7, 2005)

pH is a logarithmic number expressing how much excess H+ ions are in a solution over OH- ions (I think). So, if you want to know about the excess of H+ ions a 1.0 change in pH is a 10X change in H+ ions. But, pH is used because most things of interest are roughly proportional to pH instead of numbers of H+ ions. In other words a change from 7.0pH to 6.0 pH isn't a big change in our aquariums and a change from 7.0 to 5.0 is a lot bigger change, but not 100 times bigger as far as effects we care about are concerned.

But, when it comes to using KH and pH to measure the amount of CO2 in solution the equation that relates those three things is of the form:
CO2 = a constant times KH divided by 10 raised to the pH power. So, for that usage it is actual H+ ion excess that counts and not the log of that number.


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