Vinegar, NO, how about Acetic or muriatic acid?

[littlesilvermax]

When my tank is finally empty, I was thinking about cleaning it all out (overflow, plumbing, pumps, skimmer, etc...) by running vinegar through it for a few days.

Obviously 330 gallons of vinegar is a little costly, so I was thinking about using more pure acetic acid, and mixing to a 5% ratio (vinegar is just that, 5% acetic acid).

That is all good, but I cannot find acetic acid locally, or more specifically where to look. Any ideas?

I can get muriatic acid locally (pool supply places). Will that work? Will it harm anything?