Seachem Replenish – GH Mineral Restorer for RO/DI Water

Put back the minerals RO/DI strips out.

Reverse-osmosis and deionized water are pure — too pure. Fish adapted to mineralized water suffer osmotic stress, and in severe cases, osmotic shock and rapid death.

Seachem Replenish is a balanced blend of both “soft” (sodium, potassium) and “hard” (calcium, magnesium) salts that restores general hardness (GH) to RO or DI water, giving your fish the mineral balance their osmoregulation depends on.

Seachem Laboratories has engineered aquarium water chemistry since 1979 from its labs in Madison, Georgia, where in-house chemists formulate products that work together as a system. Replenish is built for the RO/DI keeper: rather than a single salt, it combines soft and hard salts in a balanced ratio so remineralized water more closely resembles natural water and supports healthy osmoregulation.

1. Add to RO/DI or mineral-deficient replacement water.
2. Dose to your target general hardness (GH).
3. Use at setup and with water changes.

Make pure water livable again. Add to cart.

Why Seachem Replenish

• Balanced salt blend: combines soft (sodium, potassium) and hard (calcium, magnesium) salts, not a single generic mineral.
• Protects osmoregulation: restores the GH fish rely on, preventing the osmotic stress pure water causes.
• Made for RO/DI: designed specifically to remineralize reverse-osmosis and deionized water.
• Adjustable to target: dose to your own target general hardness for the community you keep.

Best For

Fishkeepers using RO/DI or mineral-deficient water for general community and soft-water tanks who need to restore general hardness for healthy fish.

FAQ

Who needs Replenish? Anyone using RO, DI, or very soft water — it puts back the minerals that pure water lacks so fish can osmoregulate normally.

How is it different from Equilibrium? Replenish is a balanced soft-and-hard salt blend that includes sodium and potassium for general fish osmoregulation; Equilibrium is sodium- and chloride-free and aimed at planted tanks. Choose Replenish for general fish tanks and Equilibrium for planted setups.

How do I dose to a target GH? Add Replenish to your RO/DI replacement water and dose to your target general hardness, measuring GH to confirm you've reached the range your fish prefer.

What It Does

Restores general hardness (GH) to RO/DI or mineral-deficient water using a balanced blend of sodium, potassium, calcium, and magnesium salts — preventing the osmotic stress that pure water causes in fish.