Buying an acid right now is like trying to catch a falling knife you're going to get cut.

Roaches don't develop resistance to boric acid.

That will be the acid test for them. 

Then they stay put out of sight/mind away from kids or pets.There are some fairly safe dusts that are basically boric acid (Borax) and a sugar/flour mix.

What kind of acid are you on today?

You have to account for city requirements and possibility of getting a more expensive and rust friendly materials, due to the acidity of the zone.

Most people aren't aware that in order to keep the warranty in effect, you need to have the unit serviced, acid-flushed and cleaned, every year.

This would probably be true if the vapor was truly just water, but the primary ingredients in e-juice are propylene glycol and vegetable glycerin, both of which are actually a very thin oil.  

Keep 2 plungers in the house, along with Liquid Fire or other acid drain opener.