I did explain. Where else do you put it really? You put citric acid in your soil? I'm sure you have a rez even when growing in soil. Can you explain?
Your talking about cellular respiration... And citric acid is absolutely shit in a res. Why would you even use it?
As for soil... The soil will buffer the ph. That's why it's important to build it properly
What would you like me to explain? Carbonate and bicarbonate act as a buffer and will raise ph the more carbonate and bicarbonate the more acid buffering capacity you have. The type of acid used makes a big difference in terms of ph stability because they break down at different rates. Citric is a pretty weak acid to use in a res.
If you have no carbonate or bicarbonate the ph will be very unstable and the water will be highly influenced by anything that is acidic