vinegar for sure is safer way but and pricier.
You could easily dilute the acid to a required PH, simply by following my steps on having a PH probe in the tub with water prior to adding the acid.
(If you look closely at the pics of that other link wtithin this thread... that rock is ruined, I am certain you could crumb that stuff in your hands. he left it in acid for way to long (my opinion
)
I have to agree with you on that.I simply skimmed through the thread by the way the photos are presented it looks like he used way too much acid ratio to water.
On a side note
FUN FACT: you can dissolve an egg in vinegar (try that before you dip your coral in HCl
)
Me as a kid.Mom would place an egg in freshly squeezed orange juice over night.
And voila my power breakfast in the morning.