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CO2 measurement in water

2568 Views 15 Replies 11 Participants Last post by  plantbrain, 
clau74
Hi ,
How to precisely measure co2: co2 test or knowing the pH and KH using the table?
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mistergreen
A drop checker will roughly give you an idea on how much co2 is in the water.

They do make co2 sensors and meters for precise measurement but they cost thousands of dollars.
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pejerrey
In my opinion and in my experience all means to provide a "measurement" of how much co2 is in the water were rather confusing and inaccurate. I find that looking at the plant/algae growth is the best, of course taking good care of not suffocating livestock. To make sure you won't easily kill them, have good surface agitation (without splashing) and no surface scum.

And when you increase the rate of co2 make sure you are going to be around for hours to observe your livestock behavior.

Some people use the ph/KH chart, others drop checkers, I just didn't find them very useful myself. I learned to do it by watching the tank but that doesn't mean that any other technique is wrong, is just that I didn't like them.

How much To inject? As much as you can unless you have very sensitive critters.
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H
A really experienced planted tank keeper, who has been using CO2 for ages, doesn't need to mesure CO2. Someone who has never used CO2 before, but has learned that too much CO2 will kill the fish, is often told to watch the fish for signs of distress. The usual consequence of doing that is a very low CO2 level in the water, because figuring out when the fish are showing signs of distress also takes experience. That is the group for whom a drop checker is very valuable. If the drop checker is blue or blue green, no matter what the fish are doing, they aren't reacting to the CO2. If the drop checker is green, you have a significant amount of CO2 in the water. Now the new-to-CO2 group starts getting the experience to be able to judge how the fish are reacting, to see how the plants react to significant additions of CO2, and soon the drop checker will be superfluous to them too.

Measuring the KH and pH of the water is a good way to find out the KH and pH of the water.
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clau74
Hi,
Thanks guys for help! I have a question: when the relevant table of phosphate (PO4) is low and pH value and kh is correct.
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happi
clau74 said:
Hi ,
How to precisely measure co2: co2 test or knowing the pH and KH using the table?
Click to expand...

best measurement of co2 are plants, they can tell you how good the co2 is, drop checker is waste of time IME. observe the plants and see how they react to decrease or increase of co2.
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T
Drop checker is an excellent tool, and hardly a waste of time. It helps you get a new setup into the ballpark range of where your co2 needs to be. Keep turning it up till it goes green/yellow, then fine tune it from there. Using a reactor that's hidden under the cabinet? How do you know it's still working properly? The checker will let you know at a glance if it's still operating. Why wait until something looks "off" with the plants before you go looking for a problem. Saying a drop checker is a waste of time is like saying "I've been driving for 30 years, so gauges are a waste of time". You don't have to be staring at it constantly, but it certainly has it's purpose.
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happi
TwoTacoCombo said:
Drop checker is an excellent tool, and hardly a waste of time. It helps you get a new setup into the ballpark range of where your co2 needs to be. Keep turning it up till it goes green/yellow, then fine tune it from there. Using a reactor that's hidden under the cabinet? How do you know it's still working properly? The checker will let you know at a glance if it's still operating. Why wait until something looks "off" with the plants before you go looking for a problem. Saying a drop checker is a waste of time is like saying "I've been driving for 30 years, so gauges are a waste of time". You don't have to be staring at it constantly, but it certainly has it's purpose.
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the purpose, is for those who depend on it seems to run into more problems, i use to depend on the DC and had bad plant growth, it was never accurate and gave false reading, you do know that DC is almost wrong by 2 hours at detecting co2?? even worse it might show green color while your co2 are very low, making you think you have enough.
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H
happi said:
the purpose, is for those who depend on it seems to run into more problems, i use to depend on the DC and had bad plant growth, it was never accurate and gave false reading, you do know that DC is almost wrong by 2 hours at detecting co2?? even worse it might show green color while your co2 are very low, making you think you have enough.
Click to expand...
Once you get some experience, as you have, then a drop checker isn't worth the trouble, in my opinion. But, before you have that experience it keeps you from thinking you have a good level of CO2 while barely having 10 ppm. It helps keep you from letting your fear of harming the fish keep you from ever getting enough in the tank to help the plants. It is an aid many of us can use, but it isn't a way to measure the CO2 in the water with accuracy. For that a fat bank account is the best aid.
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cradleoffilthfan
I keep my drop checker closer to the yellow color, the green just doesn't seem to keep the algae away enough. I have good surface agitation and the co2 just doesn't go away. I have my co2 at close to 3 bps, actually a little under 3, but it stays yellow even during the day, at night I can only imagine. I don't have any fish though. No matter what you do, I would make sure you were around while the setup is new.
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Mathman
It would be nice for those who use fish behavior as a co2 level indicator to either describe or film what is an "odd" behavior. Thanks.
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jkan0228
Any easy way that anyone can tell if your livestock us stressed is if they're constantly at the surface of the water where oxygen is more abundant.


Sent from my fingers
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cradleoffilthfan
My Siamensis would rest on top of my drop checker which was only a few inches from the surface. As soon as I raised up the outflow to agitate the surface a bit more, he went back down to the bottom, although my drop checker never changed colors as the water was being agitated further.
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HD Blazingwolf
Mathman said:
It would be nice for those who use fish behavior as a co2 level indicator to either describe or film what is an "odd" behavior. Thanks.
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some fish become very lethargic almost stupid one could say
some respirate very rapidly and will not go to the surface just slowly die if problems are not corrected. fish will generally stay where they are comfortable which in most of our cases, is near a plant

some fish will as others have said, surface and wait there trying to grab oxygen,, i don't notice this much because good flow ensures good oxygenation everywhere, not just the surface it also takes a LOT of c02 with good oxgenation 30ppm was surpassed long ago in my tank
digital meter can't read beyond where im at anymore its range is about 55ppm +/-5
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H
When I noticed my fish in distress many of the small tetras, rasboras, were at the water surface in a corner, looking like they were gulping air from the surface. The bottom dwellers hardly moved, still at the bottom, some on their side, and some of the more colorful fish had faded colors. Those signs were often combined with a dead fish shortly after.

It helps to have a good needle valve on your regulator, because you can then easily make small changes in bubble rate, and know those changes wouldn't drift higher or lower. That made it much easier to adjust the CO2 to an optimum bubble rate. With the Milwaukee regulator I had, I used the pressure adjustment, instead of the needle valve, to make small changes in bubble rate - the needle valve wasn't nearly good enough for that purpose.

Drop checkers aren't essential, and no one is required to use them. They are cheap, easy to use, and are one more tool that some people find helpful. They are not suitable for making the final adjustment of bubble rate, because they change color too slowly, and have too big a built in inaccuracy (judging the color is very subjective). Like all tools, they can make it easier to do a job.
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plantbrain
Mathman said:
It would be nice for those who use fish behavior as a co2 level indicator to either describe or film what is an "odd" behavior. Thanks.
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You can do this yourself and likely should.

Add CO2 to the rate you think is ample.
Watch fish, with the lights on etc, turn CO2 off for a couple of hours, watch fish behavior.

Also feed a little bit before with CO2 ON...and then after 2 hours of OFF.
Note the differences.

Longer term measures: shrimp are good for breeding %, brood production.
Fish in some cases, but even at 60-70ppm CO2 I get weekly breeding from several species of fish.

I think you can use pH/KH as a relative measure, but the eyeballs and good care seem to be the most overriding factors.

Light and ferts we can measure pretty well, CO2 is more ephemeral.
Same with O2, but O2 meters work pretty well.
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