Adjusting pH: which acids and bases to use?

hello,

I'm curious, how do you determine which acids/bases to use when adjusting the pH of a solution?? ie, do I use acetic acid, HCL...or NaOH or other bases...

I was adjusting the pH of paraformaldehyde and the protocol is to use NaOH to help it dissolve into solution and then use HCl to bring it down..but why not acetic acid to bring the pH back down? Is there a basic principle I'm missing?


Please help.
Thanks!

I didn't find the right solution from the Internet.

References:
forums.biotechniques.com/viewtopic.php?f=5&t=15334#p50294



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