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Tap-Mix (RO/Tap) Calculator
Mix RO/DI water with your tap water to reach a target hardness or TDS. Perfect for soft-water fish, shrimp or discus keepers.
Mixing follows the dilution rule: tap fraction = target ÷ tap. Assumes RO water is ~0. To hit a target between two waters with known values, this calculator is exactly what you need.
Mixing Recipe
Tap Water
57.1 L
57% of mix
RO / DI Water
42.9 L
43% of mix
Resulting Value
≈ 8 dGH
uniform when mixed
Total Mix
100 L
Stir or circulate well after mixing. If using a remineralizer for RO, add it to the RO portion before topping the tank up.
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