Activity

RO water is a popular base for aquarium setups because it gives the aquarist complete control over water chemistry.

Remineralizing RO water for aquariums is not optional the way it is for drinking water.

Why RO Water Needs Remineralization for Aquarium Use

Water that is too soft, meaning too low in dissolved minerals, stresses fish and inhibits plant growth.

Soft water fish like discus and cardinal tetras thrive in low hardness water, but even they need some mineral content.

Remineralizing ro water for aquarium use means building a mineral profile matched to the species you are keeping, rather than applying a general drinking water target.

Hardness Parameters for Aquarium Water

GH, or general hardness, measures calcium and magnesium concentration.

For freshwater planted tanks, a GH of 4 to 8 dGH is a common target, equivalent to roughly 70 to 140 ppm.

KH should not be zero even in soft water tanks.

How to Remineralize RO Water for Aquarium Use

Follow the manufacturer’s dosing instructions and verify with a GH test kit before adding the water to the tank.

Seachem Equilibrium is a commonly used option for planted freshwater tanks.

Changes to tank water chemistry should be made gradually to avoid stressing fish.

What Plants Need That Fish Do Not Always Need

Calcium and magnesium are required for plant cell structure and chlorophyll production.

Remineralizing ro water for aquarium planted tanks should include a formulation that lists calcium and magnesium specifically.