aquabillpers;15018 said:
I'm satisfied that the test kits I use are close enough to "the truth" when water chemistry is within normal ranges. (And, no, I haven't calibrated them, but the readings are consistent over time and with different batches of test kits.)
I do wonder, though, what is the "optimum" CO2 level in a high light tank. Are there any experiments that quantify the differences between, say, 15 ppm and 50 ppm?
I suspect that there isn't a lot of difference, but I really don't know.
Bill
Yes, Van et al 1976 dicussed this in detail over a wide range of light intensities.
They found that the 3 aquatic weeds saturate at about 600micromoles of light and about 30-40ppm of CO2.
Fun tropical midday sun = 2000micromoles
Adding more does not increase photosysnythesis.
Some plants may have species to species differences etc, but this is a good general range.
If you added say 50-70micromoles of light , then 15 ppm is likely fine of CO2.
Which was the case about 10-20 years ago.
Since folks have added more light, now they need more CO2.
If you add good CO2 at low light, then you have excellent growth, healthy, easier to manage/prune etc, dose nutrients, less issues targeting good CO2 levels etc.
If you look at optimal CO2, you need to see in what context with respect to light.
Light drives the CO2, and NO3 etc can regulate CO2 uptake if limiting as can PO4 etc.
Regards,
Tom Barr