I think the best way to approach it with the shop lady, since you seem to have a rapport with her, and you two can talk, would be this: Bring up that you found Angels and Barbs are better in softer waters, let her explain her take on it. She may have tricks that she has yet to share, a learning plateau she may help you obtain. If she has old drift wood, it may soften and some people filter with peat... I would start by asking her what the scoop is but go in to the discussion with facts, and even those things that seem right to you, but are more hand-me-down stories... get her talking! She maybe more information than we know, ... or she is just trying to sell her wares.... But those old folks that have been doing this for donkeys years, have their ways and many of those work as well as all the chemicals