How do you keep your ripariums/paludariums from developing hard water stains?
I'm interested in making a 30 gallon-ish paludarium with enough water area to keep white cloud mountain minnows.
Like 1/3 to 1/2 of the tank. The land would on a false bottom, planted with water-loving plants, and have isopods/springtails. Maybe a semi-aquatic frog if the setup does well. It's still an idea at this stage.
However, I'm worried that using tap water would cause a line of stain at water level.
How do you guys deal with that?
I was thinking of using RO drinking water (not RO/DI), as an alternative.
Just cutting it with (hard) tap water to re-mineralize it.
Then I read that RO/DI water re-mineralized enough with contact with the environment that it isn't detrimental to dart frogs.
That got me wondering if RO water (during a water change) would be able to re-mineralize enough from contact with the land area/established water of a paludarium to not harm the white clouds?
I don't want to risk experimenting with this so I thought I'd for the community's thoughts on this.