1) flush medium with a half strength solution . if you normally run a 800 ec or 4 ml a liter, use 2 ml a liter.
the reason is to remove ALL the old unbalanced solution and replace it with a balanced solution. a mild salt solution will take out more salts quicker than plain water( like growing salt crystal on a string ) as well as replacing them with fresh solution.
2) water as normal when needed.
there is never a time...ever...ever ..that a plant needs only one or two minerals without the rest as well.