Seachem Replenish is specially designed to replenish physiologically needed minerals that have been removed during reverse osmosis or deionizing filtration. Designed to replenish physiologically needed mineralsRestore General Hardness (GH) using "soft" and "hard" saltsHelps prevent sudden death due to osmotic stressReplenish will restore General Hardness (GH) using "soft" and "hard" salts. This special blend of salts will help prevent sudden death due to osmotic stress which causes osmotic shock. Dosage: 500 ml (16. 9 oz) treats 1,000 gallons. Directions: Add 5 mL (1 capful) Replenish to 10 Gallons to raise GH by 1 meq/L (2. 8 dGH). Recommended restoration level into DI or RO water is 1-2 meq/L which is 5 mL per each 5-10 gallons.