Need some advice on how to properly clean some rock

[eli@fijireefrock.com]

i would say a couple days.
i would add a PH probe to keep an eye on the fluctuation.
keep in mind if you are mixing water and vinegar you will end up diluting the acidity of your mix.(tap water usually hovers around 7.5 PH.
Anything below 6.5 ph should be fine for an acid solution.
A higher solution will do nothing to your rocks.
My numbers could be a bit off.