# how do I determine how much CO2 I need and how much I'm putting in?



## tjurhs (Mar 31, 2014)

Hey guys,

I'm brand new to the CO2 stuff, and hopefully I'll have my system up and running soon...

Is there a thread or other website where I can calculate how much CO2 should be put into my tank?

and then, other than the bubble counter, is there some way to determine how much I am actually putting in?

Thanks much for your help!

Todd


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## Aqua Newbie (Apr 18, 2014)

i use a drop checker


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## MamaJu (Jun 4, 2013)

I second that... use a drop checker.


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## mfurufuru (Mar 20, 2012)

How big is your tank? Like they said you need a drop checker. Place it on the other side of your tank from where your co2 diffuser is located. It will take a few hours for the color to change but it should turn from blue to green. If it is green you have enough co2.


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## OVT (Nov 29, 2011)

IMHO, the drop checker is an evil fish-killing $10 gizmo. By the time it is the color you *think* it should be, your fish is long dead. Different species have different co2/o2 tolerance levels and no fish cares about your drop checker color.

Instead of relying on unreliable crutch do it the hard way: start low, increase slow, and watch your real limiting factor: your fish.

v3


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## buckwheet (Apr 29, 2014)

tjurhs said:


> Hey guys,
> 
> I'm brand new to the CO2 stuff, and hopefully I'll have my system up and running soon...
> 
> ...



1) yes, your shooting for 25-35ppm. you'll need the drop checker, some 4dkh solution (don't use tank water) you can make your own or buy it.
it's very cheap and it'll last you a long time.
use the bromothymol blue found in any PH test kit.
and a KH test kit

2) for co2 ppm you use a color chart to cross reference KH, and then PH drop (by color change) to determine the amount in the tank













(some reading to help you before you start):thumbsup:

http://www.aquariumslife.com/aquascaping/fertilizers-and-co2/drop-checke/

http://www.barrreport.com/showthread.php/2818-Drop-Checkers-CO2-Indicators-Why-and-How

http://www.barrreport.com/showthread.php/12022-CO2-pH-KH-table

http://www.barrreport.com/showthread.php/6941-Ready-made-drop-checkers-vs-4dkh-solutions


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## acitydweller (Dec 28, 2011)

start using your bubble counter and add upwards through adjustments over time. This tuning is a necessary evil as the factors vary by available water volume, surface tension, filtration turnover, plant density just to name a few. All these variables will effect the rate of co2 needed to sufficiently saturate the aquarium but know that its far easier to overdose and kill all fish than it is to master this tuning so work your way up rather than down. Start by 1bps and adjust over a few days after watching where the tank is after 3-4 hours. Are the plants pearling or have you seen noticible growth in some of the plants you are familiar with?


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## MeCasa (Apr 22, 2014)

Will it not help the plants if you add small amounts of CO2 right at the plants while not saturating the entire tank?

Thanks


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## Steve002 (Feb 7, 2014)

A drop checker gives an indication of the CO2 disolved into the checker's testing solution. The CO2 first has to out gas from the aquarium water into the air pocket in the checker and then into the solution itself and this all takes time, a few hours anyway. As such it is not much good as an immediate measure of the CO2 in the tank and as OVT points out that by the time it has indicated a change in color the fish may well be stressed.
It is a good day to day check on CO2 levels however. I usually look at mine in the morning to see that the color has gone back to a greenish blue and then again when I'm home from work to see the lime green color. If I notice a change in the colors it becomes a good indication something has changed and I need to look at it to determine what.
As the others say turn your CO2 up a little bit at a time each day and monitor your fish's activity and the color on the checker. Do the KH/PH testing if you want or need more accuracy. I keep my CO2 up fairly high to combat algae and I notice the fish will be less active at this time. When the CO2 shuts down and the air pump starts up the bubbles their activity begins to pick up again. When I add new fish I try to do so at lower CO2 levels as they take a bit of time to get used to it and can be seen up near the surface to begin with.


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## tjurhs (Mar 31, 2014)

GLA drop checkers are expensive!

OVT, I have no fish, so let it kill them that don't exist  

BUT! so long as the CO2 won't kill my snails, I like my snails!

I already have a API pH kit, will the KH kit have directions to follow to test for CO2 amounts? what is meant by "to cross reference KH"

buckwheat, PERFECT, thanks for the chart and the reading links!


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## Kntry (Dec 26, 2013)

Do you have to change the drop checker fluid?

According to my drop checker, green, the CO2 is good. If I use the above chart, it's 35. Which is correct?

Do you need to turn the lights on before the CO2 comes on and turn them off after the CO2 goes off? If you have canister filters, do you still need an airstone?

I hope you don't mind the extra questions since we both need to learn.


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## Darkblade48 (Jan 4, 2008)

Kntry said:


> Do you have to change the drop checker fluid?
> 
> According to my drop checker, green, the CO2 is good. If I use the above chart, it's 35. Which is correct?
> 
> ...


I change out my fluid about once a month. It's cheap enough to do it more often, if you want.

A drop checker is a rough way of estimating the amount of CO2 you have; if anything, it only serves as a visual indication to check that you have about 30 ppm of CO2.

Most people have the CO2 come on about 30 minutes before the lights, and go off 30 minutes before the lights (the opposite of what you stated). This is so that when the lights come on, there is already CO2 in the water that plants can use. Of course, when there is no light, plants are not photosynthesizing, and CO2 is not required.

An airstone is not necessary if you have your CO2 turning off at night (regardless of whether you are using a canister filter or not).


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## Kntry (Dec 26, 2013)

Thank you for straightening me out! I'm new to this.


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## buckwheet (Apr 29, 2014)

"will the KH kit have directions to follow to test for CO2 amounts?"

no. the test kit tests KH only. 

" what is meant by "to cross reference KH"

this is how you get an estimate for CO2 ppm
on the left of that chart (going down) is KH, above, (left to right)
is PH.
so you test your water for KH (*me* 3.5ish) 
then PH (*me* 7.5)
so I look at the KH side at 3.5, move left to right till I get to what is 33.2ppm on the chart. then move up and I see i'll need to inject the CO2 till I get around a 1.0 drop in PH (7.5 to 6.5) and that *puts me around* 
33 ppm of CO2roud:

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"Measured your KH, then see how much you need to reduce the pH to get your target CO2 ppm.

Say you tap water is a KH of 5m say you want 35-40ppm of CO2, you should add enough to get the pH to 6.6 and be able to keep it there.

Warning, KH may not be entirely carbonate hardness. This means you will think and believe you have MORE than you actually do, thus you may be under dosing CO2.
This issues will never be the reverse, eg, you are adding more CO2 than you think.

So the error is always on the safe side usign this method.

As the KH in your tap drops, say your KH is 1-2 degrees, there's just not much room for other sources of KH other than carbonate, at 4-5 and above, there may be.
So assuming most of the KH is carbonate hardness for a KH or 1 degree is likely okay.

Say you want a CO2 of 50 ppm for a KH of 1 degree? the chart does not cover those ranges of pH's, but you can scale using a similar higher KH to see what the pH adjustment would be.
So about 5.9 pH would give about 39 ppm and a pH of 5.8 would give about 48 ppm of CO2."

_-----tom barr------_


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## zachawry (May 28, 2013)

Granted, I'm a newbie at this stuff, but the guy at the LFS, who has been very knowledgable about everything else, said a drop checker was unnecessary. He said, "Just use a bubble counter at 3-5 bubbles per second. Make sure your fish aren't showing signs of CO2 distress. Increase if you want a little more growth. Dial back if you want to slow down your growth."

This approach has served me admirably well so far. I have great growth. I have healthy fish. Worst comes to worst, I'm wasting a few dollars in CO2 per month. Who cares? 

Can anyone who is more knowledgable than I am point out what is wrong with this approach? 

Zachary 

------
My heavily-planted discus tank: 
https://www.youtube.com/watch?v=o2085NurXh4
https://www.youtube.com/watch?v=0KgRIQY6Mqw


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## tjurhs (Mar 31, 2014)

thanks buckwheat! that chart is super helpful!

Zachary, that sounds pretty good to me.

so between the two, I think I have a good approach.

will too much CO2 kill my snails?


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## Darkblade48 (Jan 4, 2008)

zachawry said:


> Granted, I'm a newbie at this stuff, but the guy at the LFS, who has been very knowledgable about everything else, said a drop checker was unnecessary. He said, "Just use a bubble counter at 3-5 bubbles per second. Make sure your fish aren't showing signs of CO2 distress. Increase if you want a little more growth. Dial back if you want to slow down your growth."
> 
> This approach has served me admirably well so far. I have great growth. I have healthy fish. Worst comes to worst, I'm wasting a few dollars in CO2 per month. Who cares?
> 
> ...


Absolutely nothing wrong with this approach. Some people still use this method if they want to keep things simple.

The only caveat is that bubble rate is not a good indicator of how much CO2 is actually making its way into the water column. Furthermore, large aquariums will need much higher injection rates to see any appreciable difference in CO2 saturation.





tjurhs said:


> will too much CO2 kill my snails?


Yes, it is possible, but more likely, your fish will show signs first. 

High amounts of CO2 over a long period of time can slowly erode away snail shells, however.


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## tjurhs (Mar 31, 2014)

thanks Anthony!

I have no fish so I'm not worried about killing them 

so please help me with this question about implementation of CO2:

my regulator is manually turned on and off. my lights are on a timer because I'm not home all day. I know/think that it would be best to have both the lights and the CO2 on and off at the same time, but that can't happen (unless I get an electronic regulator, which I don't plan to). so is CO2 injecting into the tank while the lights are off, wasted CO2 ? will it over inject the CO2 because there is no light to use? do guys with manual regulators turn them off when the lights?

Thanks for your help


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## Steve001 (Feb 26, 2011)

tjurhs said:


> thanks Anthony!
> 
> I have no fish so I'm not worried about killing them
> 
> ...


My tank is a 47 gallon tank. I use a 20lb Co2 tank. It lasts over a year.

A few decades ago I started injecting co2 continuously just like nature does. Not once have I ever caused stress to the fish. I also don't have to worry about solenoid failure, resetting timers after a power outage because the are no electronics controlling the injection of co2. My tank has always been heavily planted with a low fish population. When you place emphasis on plant population over fish population you will avoid many problems. With that in mind those plants will provide enough O2 to keep the fish breathing easily overnight.


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## tjurhs (Mar 31, 2014)

thanks Steve!

what I hear you saying is turn on the CO2 (and fiddle with it till you get the right settings/amounts) and then just let it run, don't worry about turning it on or off, correct?


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## Darkblade48 (Jan 4, 2008)

tjurhs said:


> so please help me with this question about implementation of CO2:
> 
> my regulator is manually turned on and off. my lights are on a timer because I'm not home all day. I know/think that it would be best to have both the lights and the CO2 on and off at the same time, but that can't happen (unless I get an electronic regulator, which I don't plan to). so is CO2 injecting into the tank while the lights are off, wasted CO2 ? will it over inject the CO2 because there is no light to use? do guys with manual regulators turn them off when the lights?


It would be best to have both the lights and CO2 on a timer, but as mentioned, most people tend to have the CO2 turn on 30 minutes before the lights and 30 minutes before the lights turn off (though this is not absolutely necessary). 

If you do not intend to get a timer and solenoid (there is no such thing as an "electronic regulator"), then you can leave the CO2 injecting 24/7. Any CO2 that is injected when the lights are off will be wasted, as the plants will not be photosynthesizing.

It is possible to over-inject CO2 during this time, causing stress to livestock, as plants will be respirating and producing CO2 in addition to the injected CO2.


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## tjurhs (Mar 31, 2014)

Hi Anthony,

I read your CO2 Primer and now I understand that I meant an electrically powered solenoid, not regulator. This is my Intense regulator and I have a standard US paintball tank, what would be a good electrically powered solenoid that would fit between the two? and then I can put it on a timer

Thanks much, Todd


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## buckwheet (Apr 29, 2014)

zachawry said:


> Granted, I'm a newbie at this stuff, but the guy at the LFS, who has been very knowledgable about everything else, said a drop checker was unnecessary. He said, "Just use a bubble counter at 3-5 bubbles per second. Make sure your fish aren't showing signs of CO2 distress. Increase if you want a little more growth. Dial back if you want to slow down your growth."
> 
> This approach has served me admirably well so far. I have great growth. I have healthy fish. Worst comes to worst, I'm wasting a few dollars in CO2 per month. Who cares?
> 
> ...




I see nothing wrong with it!:thumbsup:

I keep mine in the tank for about 4-6 days, after a bottle change.
then out it go's after I know I'm back to being dialed in. 
a bubble counter may just be a good comfort tool as a starting point to some. a useless tool to others. but to most, an eye sore!...........lol


buy the way..................SWEET looking discus tank!


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## Steve001 (Feb 26, 2011)

tjurhs said:


> thanks Steve!
> 
> what I hear you saying is turn on the CO2 (and fiddle with it till you get the right settings/amounts) and then just let it run, don't worry about turning it on or off, correct?


 Yup, that's right.


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## tjurhs (Mar 31, 2014)

is it a good thing to have a larger sized diffuser?

it would seem to me that if the same amount of CO2 is being dispensed through a larger diffuser (with therefor larger surface area) more CO2 would be dispersed throughout the tank and therefor absorbed into the water.

or does a larger diffuser require more CO2 coming from the regulator?


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