Seachem Replenish 250 mL – Freshwater GH Mineral Supplement

Seachem Replenish 250 mL is a freshwater mineral supplement designed to restore general hardness in water treated by reverse osmosis, deionization, or other purification methods. It replaces physiologically relevant minerals that fish need to maintain a proper balance of water and salts within their bodies.

Replenish contains a balanced blend of calcium, magnesium, potassium, sodium, and other mineral salts. It raises general hardness without functioning as a carbonate buffer, making it useful when GH needs to be restored separately from KH and pH.

Key Features

• Restores General Hardness: Replenishes minerals removed by reverse-osmosis or deionization filtration
• Supports Fish Osmoregulation: Helps provide the mineralized environment required by many freshwater fish
• Balanced Mineral Blend: Contains calcium, magnesium, potassium, sodium, and other physiologically relevant salts
• Raises GH: Increases general hardness without acting as a carbonate-hardness buffer
• Ideal for Purified Water: Useful for remineralizing RO, DI, distilled, and mineral-deficient freshwater
• Convenient Liquid Formula: Easy to measure and mix into replacement water during aquarium maintenance
• 250 mL Bottle: Suitable for nano, small, and medium freshwater aquariums

Product Information

• Brand: Seachem
• Product: Replenish
• Size: 250 mL
• Equivalent Size: Approximately 8.5 fl oz
• Product Type: Freshwater general-hardness mineral supplement
• Primary Use: Remineralizing RO, DI, distilled, or mineral-deficient water
• Aquarium Type: Freshwater fish aquariums
• Standard Dosage: 5 mL per 10 gallons
• GH Increase: Approximately 1 meq/L or 2.8 dGH per standard dose

Best Used For

• Freshwater fish aquariums using RO or DI water
• Distilled or highly purified replacement water
• Freshwater systems with insufficient general hardness
• Fish-only community aquariums
• Soft or mineral-deficient source water
• Preparing replacement water before a water change
• Preventing osmotic stress caused by mineral-free water
• Maintaining stable GH for freshwater fish

How to Use

Add one capful, or 5 mL, of Seachem Replenish for every 10 US gallons of replacement water. This raises general hardness by approximately 1 meq/L, which is equal to about 2.8 dGH.

For best control, add Replenish to a separate container of RO, DI, or distilled water before the water is added to the aquarium. Mix thoroughly, test the GH, and adjust gradually until the replacement water matches the requirements of the fish being kept.

Dosage may be adjusted according to the starting hardness and desired GH. Avoid making sudden changes to an established aquarium’s mineral concentration.

Approximate Dosage Guide

• 2.5 Gallons: Approximately 1.25 mL raises GH by about 2.8 dGH
• 5 Gallons: Approximately 2.5 mL raises GH by about 2.8 dGH
• 10 Gallons: 5 mL raises GH by about 2.8 dGH
• 20 Gallons: 10 mL raises GH by about 2.8 dGH
• 40 Gallons: 20 mL raises GH by about 2.8 dGH
• 55 Gallons: Approximately 27.5 mL raises GH by about 2.8 dGH
• 75 Gallons: Approximately 37.5 mL raises GH by about 2.8 dGH

These amounts are proportional calculations based on Seachem’s standard dosage. Always test the prepared water and follow the current instructions printed on the bottle.

Adjusting to a Desired GH

One standard dose raises GH by approximately 2.8 dGH. To achieve a larger increase, multiply the standard dose proportionally.

• Increase by approximately 2.8 dGH: Use 5 mL per 10 gallons
• Increase by approximately 5.6 dGH: Use 10 mL per 10 gallons
• Increase by approximately 8.4 dGH: Use 15 mL per 10 gallons

Make large mineral adjustments gradually, particularly when fish are already inside the aquarium. Preparing replacement water separately helps prevent abrupt GH changes.

Why General Hardness Matters

General hardness measures primarily dissolved calcium and magnesium, along with other multivalent mineral ions. These minerals contribute to normal osmoregulation and other biological processes in freshwater fish.

Completely mineral-free water may cause osmotic stress in fish adapted to mineralized environments. Severe osmotic stress can lead to osmotic shock, which may become life-threatening.

Replenish and KH

Replenish is intended to restore general hardness. It is not a carbonate-hardness buffer and should not be relied upon to establish or stabilize KH.

RO and DI water may have very little buffering capacity. A separate aquarium buffer may be needed when the aquarium requires a specific KH or stable pH. Choose a buffer that matches the needs of the fish being kept.

Replenish and pH

Replenish is not designed as a pH-adjusting product. However, mineral additions and changes in aquarium chemistry can sometimes produce indirect changes in measured pH.

Test GH, KH, and pH separately when preparing purified water. Do not assume that restoring GH automatically creates the correct KH or pH for the aquarium.

Replenish vs. Equilibrium

Seachem recommends Replenish primarily for fish-only freshwater aquariums. For planted aquariums, Seachem recommends Equilibrium, which is formulated to restore mineral content while supporting the needs of aquatic plants.

Replenish should not be marketed as the preferred remineralizer for planted aquariums. Aquariums containing substantial live-plant growth may be better served by a plant-focused product such as Seachem Equilibrium.

Using Replenish in Shrimp Aquariums

Shrimp species have different GH, KH, and mineral requirements. Replenish is not specifically formulated as a shrimp remineralizer, and the correct mineral balance depends on the shrimp species being maintained.

Test GH, KH, pH, and total dissolved solids before using any mineral supplement in a shrimp aquarium. A shrimp-specific GH or GH/KH remineralizer may provide more targeted mineral ratios for sensitive shrimp species.

Water-Preparation Tips

• Prepare RO or DI water in a separate clean container
• Add Replenish before placing the new water in the aquarium
• Mix thoroughly and allow the minerals to distribute evenly
• Test GH after mixing
• Test KH and pH separately
• Match replacement-water temperature to the aquarium
• Use an appropriate water conditioner when tap water is included
• Avoid sudden changes in GH or total dissolved solids
• Base the target hardness on the species being kept

Important Aquarium Care Note

Replenish should be dosed according to measured water hardness and the needs of the aquarium livestock. Adding excess minerals without testing may create water that is harder than intended.

Replenish does not remove chlorine, chloramine, ammonia, nitrite, nitrate, or other contaminants. It also does not replace water conditioning, filtration, cycling, water testing, or regular aquarium maintenance.

Do not add mineral supplements solely because fish appear stressed. Test the water and identify whether GH, KH, pH, temperature, ammonia, nitrite, or another condition is contributing to the problem.

Frequently Asked Questions

What is Seachem Replenish used for?
Seachem Replenish restores general hardness and physiologically relevant minerals in RO, DI, distilled, or mineral-deficient freshwater.

How much Replenish should I use?
Use 5 mL for every 10 US gallons of water. This raises general hardness by approximately 1 meq/L, or 2.8 dGH.

Does 5 mL per 10 gallons raise GH by 1 dGH?
No. The official standard dose raises GH by approximately 2.8 dGH.

Does Replenish raise KH?
Replenish is designed to restore GH and does not function as a carbonate-hardness buffer. Test and adjust KH separately when needed.

Does Replenish change pH?
It is not formulated as a pH-adjusting product. Test pH after preparing the water because changes in overall mineral chemistry can sometimes affect measured values.

Can Replenish be used with RO or DI water?
Yes. Restoring minerals removed by reverse-osmosis and deionization filtration is the product’s primary purpose.

Can Replenish be used with tap water?
Yes, when testing shows that the tap water or tap-and-RO mixture does not contain enough general hardness for the fish being maintained.

Is Replenish recommended for planted aquariums?
Seachem recommends Equilibrium for restoring GH in planted aquariums. Replenish is primarily intended for fish-only systems.

Is Replenish specifically designed for shrimp tanks?
No. Shrimp species may require specific mineral ratios, GH, KH, and total dissolved solids. Consider a shrimp-specific remineralizer when appropriate.

Should I use a GH test kit?
Yes. Test the starting water and the prepared replacement water so the dosage can be adjusted accurately.

Should Replenish be added directly to the aquarium?
It may be added according to the label, but mixing it into replacement water before a water change generally provides better control and reduces the risk of sudden mineral changes.

Does Replenish replace a water conditioner?
No. It does not remove chlorine or chloramine. Use an appropriate water conditioner whenever untreated tap water is used.

Available at Tropical Treasures Wyo

Seachem Replenish 250 mL restores general hardness and essential minerals in RO, DI, distilled, and mineral-deficient freshwater. Visit Tropical Treasures Wyo in Cheyenne, Wyoming, to shop Seachem freshwater supplements, GH and KH test kits, water conditioners, remineralizing products, filters, and aquarium care essentials.

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