I recently installed a CO2 meter: Water Management Technologies, Inc. - OxyGuard Products - Portable Dissolved CO2 Analyser
I took some readings in several tanks over a few hours and saw a wider range than many have ever suggested. I've long suspected localized areas of CO2 variation, and suggested increasing current to compensate. Many hobbyists have logn assumed that the CO2 concentrations have been homogeneous/the same throughout the entire tank.
I've long claimed otherwise.
Thus many hobbyists have still enjoyed their speculation about nutrients being the cause of all algae and plant issues. However, if we consider the role of CO2 and C in plant growth, it stands to reason that it must pay an enormous role.
"Oh here Tom goes again, claiming it's all about CO2, just add more and mircles will occur"
However, now the data using a device that can measure very accurately to within 1 ppm CO2 suggest I was right all along.
Some data on a 180 gallon tank with high light, ADA AS, good dosing and very high flow(3000 gph):
Near out flow of the filter from which a venturi CO2 input originates:
5 cm away: 40-100ppm
30-40 cm away: 20-30ppm
Within the plant beds: 8-12 ppm
Now for a 20 Gallon tank with 250 Gallons per hour flow:
5 cm from CO2 source: 35ppm
15 cm: 30ppm
30 cm: 22ppm
50 cm 17ppm
Within plant beds(dense): 6-12ppm
Note, these are just averages.
Response time is about 1ppm.
Some interfering ions for pH/KH that are common:
Ammonium, PO4, borates, hydroxides, all things that are present in most planted tanks.
This method gets around that, gives accurate fast readings
It's more accurate than the pH/KH table assuming it is correct ands all the Carbonate is Alkalinity and that the pH is only influenced by bicarbonate and CO2.
Still, this verifies, that even in smaller system and particularly in larger systems, the role of both current and CO2.
Why speculate when we can measure? Verify?
Test our assumptions and hypothesis and discard those that we cannot find evidence for?
Seems like a poor argument and method to sit around and speculate, criticize and not get any resolution. A "who can yell louder" match is a typical web debate on many such topics, rather than anything that follows a logical path to a better understanding.
I think that this meter did this job and verified what I'd been suggesting all along.
I checked the calibration a few times and it was dead on. The nice thing here is that you can quickly measure dose response effects. Add a bit more CO2, watch the meter pick up the increase really fast. The other thing is where hobbyists have been measuring their CO2, either the drop checker, the pH probe or the water sample. KH is stable throughout but pH may very well not be in relation to small(actually quite large) changes in CO2.
The meeter can be moved around throughout a day and check various spots, even the leaves of a specific plant!
I also measured 30ppm in a Discus tank and we sat and noted no differences in behavior, something I've also said for years but many discus folks have long claimed otherwise.
Then when shown this data, they back tracked and said, well, "the fish need to slowly acclimate to CO2, and get use to it over time".
Yet respiration is not like osmoregulation.
So........even when faced with such evidence, they try and weasel out of it.
One thing that shocked me a bit was just how tolerant fish are to higher levels of CO2. I'd predicted much less. 105ppm and the large school of cardinals where fine. But I find such information interesting and am happy to discard such theories when they are wrong.
The next step would be to use a current flow meter that can measure small ranges in situ along with CO2.
I'll do some more presentation of data and also bring in O2 data from the Hach LDO meter so we can compare both O2(plant growth) and CO2 demand/uptake simultaneously.
Likely the next BR newsletter.
Regards,
Tom Barr
I took some readings in several tanks over a few hours and saw a wider range than many have ever suggested. I've long suspected localized areas of CO2 variation, and suggested increasing current to compensate. Many hobbyists have logn assumed that the CO2 concentrations have been homogeneous/the same throughout the entire tank.
I've long claimed otherwise.
Thus many hobbyists have still enjoyed their speculation about nutrients being the cause of all algae and plant issues. However, if we consider the role of CO2 and C in plant growth, it stands to reason that it must pay an enormous role.
"Oh here Tom goes again, claiming it's all about CO2, just add more and mircles will occur"
However, now the data using a device that can measure very accurately to within 1 ppm CO2 suggest I was right all along.
Some data on a 180 gallon tank with high light, ADA AS, good dosing and very high flow(3000 gph):
Near out flow of the filter from which a venturi CO2 input originates:
5 cm away: 40-100ppm
30-40 cm away: 20-30ppm
Within the plant beds: 8-12 ppm
Now for a 20 Gallon tank with 250 Gallons per hour flow:
5 cm from CO2 source: 35ppm
15 cm: 30ppm
30 cm: 22ppm
50 cm 17ppm
Within plant beds(dense): 6-12ppm
Note, these are just averages.
Response time is about 1ppm.
Some interfering ions for pH/KH that are common:
Ammonium, PO4, borates, hydroxides, all things that are present in most planted tanks.
This method gets around that, gives accurate fast readings
It's more accurate than the pH/KH table assuming it is correct ands all the Carbonate is Alkalinity and that the pH is only influenced by bicarbonate and CO2.
Still, this verifies, that even in smaller system and particularly in larger systems, the role of both current and CO2.
Why speculate when we can measure? Verify?
Test our assumptions and hypothesis and discard those that we cannot find evidence for?
Seems like a poor argument and method to sit around and speculate, criticize and not get any resolution. A "who can yell louder" match is a typical web debate on many such topics, rather than anything that follows a logical path to a better understanding.
I think that this meter did this job and verified what I'd been suggesting all along.
I checked the calibration a few times and it was dead on. The nice thing here is that you can quickly measure dose response effects. Add a bit more CO2, watch the meter pick up the increase really fast. The other thing is where hobbyists have been measuring their CO2, either the drop checker, the pH probe or the water sample. KH is stable throughout but pH may very well not be in relation to small(actually quite large) changes in CO2.
The meeter can be moved around throughout a day and check various spots, even the leaves of a specific plant!
I also measured 30ppm in a Discus tank and we sat and noted no differences in behavior, something I've also said for years but many discus folks have long claimed otherwise.
Then when shown this data, they back tracked and said, well, "the fish need to slowly acclimate to CO2, and get use to it over time".
Yet respiration is not like osmoregulation.
So........even when faced with such evidence, they try and weasel out of it.
One thing that shocked me a bit was just how tolerant fish are to higher levels of CO2. I'd predicted much less. 105ppm and the large school of cardinals where fine. But I find such information interesting and am happy to discard such theories when they are wrong.
The next step would be to use a current flow meter that can measure small ranges in situ along with CO2.
I'll do some more presentation of data and also bring in O2 data from the Hach LDO meter so we can compare both O2(plant growth) and CO2 demand/uptake simultaneously.
Likely the next BR newsletter.
Regards,
Tom Barr