Advice Please: Who runs cannister filters on their Reef and other things

[Slick Fork]

Originally Posted by Skimmer King

Distilled RO/DI water will do the same thing let it sit stale for 1 day in a glass.

That's good for zeroing it, but there are a lot of refractometers that don't scale properly which is why I've always seen it recommended that you calibrate it at 35