Prow you just never want to listen do you when you are in error
You are digging post holes here buddy. Where in the quote is the word CO2. Where does it say that a low alk is affect more so or less so by CO2 in dropping or raising the pH. Where does its say that a buffer buffers out CO2 ? Randy will tell you flat out that CO2 is a different issue. He says so in the article you posted. How many times do I have to say that Alk is not effect by CO2 and CO2 is not effected by Alk. And how many times do I have to say that no mater what the Alk if CO2 enters the system there will be a drop in pH no matter what the Alk is. CO2 is NOT part of the buffer system and CO2 is NOT part of Alk. In short, you don't understand pH, CO2 and Alk relationships. I guess Randy and I are all wrong then on the chem forum on our 100's of posts like mine here all saying the same thing. Go have a look.
They only one that need to shut-up is yourself
You post something without reading the whole article. How'd did you miss this
The fundamental explanation is that the tank is deficient in CO2. In effect, the tank has an internal pCO2 that is more like that for the preindustrial air with 273 ppm CO2 (Figure 2). In this case, driving more CO2 from "normal air" into the water ****would lower the pH to about 8.2-8.3 while maintaining the same alkalinity.****
Where does he say that an alkalinity of any value is going to stop this from happening.
Likewise, tanks that use calcium carbonate/carbon dioxide reactors often have a pH of 8.0 with an alkalinity of 3 meq/L (or more). Again, that set of values falls off of the theoretical curve shown in Figure 2. In this case, the tank has an artificially high internal pCO2 of more than twice "normal air". Driving more CO2 from the tank into "normal air" ****would raise the pH to about 8.2-8.3 while maintaining the same alkalinity.***
And what is he saying ? What I just said AGAIN
that no mater what the Alk if CO2 enters the system there will be a drop in pH no matter what the Alk is.
You high-lited
The change in pH, however, is made smaller when an appropriate buffer is used.
Of course it does the more buffer the higher the pH and Alk, depending on the buffer used. That is why one adds BS as it has much less impact on pH than say BBS does. So what's new. You should know that if you add BS and watch the pH upon addition what happens to the pH even though the Alk has gone up Prow. The pH drops doesn't it ? But what, the Alk is now even higher and did not stop the CO2 addition from the buffer and stop the pH from falling now did it
It still dropped. Do you see where I'm going here ?
Consequently, marine aquaria with higher alkalinity tend to have greater buffering against pH swings
Yup unless there is an increase in CO2 then it drops no mater what the Alk is for the 100th time
Go back and re-read Randy's quote.
A buffer is something that helps minimize pH changes in the presence of added acid or base
See those words, "Base and Acid". CO2 is a gas and has no charge correct ? So, it is not a base or acid correct ? Unless it gets converted. What happens, in short, is in the reactions we could say, that the CO2 does drop the Alk. However, when the reaction is all complete there is a net gain in short of 1 H+ and 1 OH- and the two cancle themselves out and the Alk remains thte same.
Did you know and most that do know me know, that my favorite subject in this hobby is the CO2/Carbonate System along with GAC? And you want to argue about it.
The pH of water is dictated by the amount % of CO2, HCO3- and CO3-. If the pH drops from 8.3 to 8.2 there will be more CO2, more HCO3- and less CO3--. If we raise the pH to 8.4 there will less CO2 and more HCO3- and CO3--. Here is a graph to show this, it is called a pC-pH diagram.