Reef Builder 600 g — KH Alkalinity Without pH Impact | Seachem

Seachem Reef Builder is a powdered alkalinity supplement that increases carbonate hardness (KH) with minimal and gradual impact on pH. With long-term use, the pH will tend to stabilize at 8.3. Unlike competing products based solely on sodium bicarbonate, which can lower pH, Reef Builder uses a blend of carbonate sources that does not deplete calcium, magnesium, or strontium when used as directed.

Main advantages

• Increases carbonate alkalinity (KH) without immediately affecting pH
• Blend of carbonate sources — does not lower pH like bicarbonate-only products
• It does not deplete calcium, magnesium, or strontium.
• Gradually stabilizes the pH at 8.3 with long-term use
• Compatible with pre-mixed solution dosing pumps

Use in reef aquariums

Carbonate alkalinity is essential for the growth of all corals. Seachem recommends maintaining alkalinity between 3 and 5 meq/L (8–14 dKH), never dropping below 2 meq/L. The Reef Builder and Seachem Reef Buffer can be used together: the Reef Builder to increase alkalinity without altering the pH, and the Reef Buffer to increase both alkalinity and pH simultaneously. When pH is not a concern and only alkalinity needs correction, the Reef Builder is the preferred choice.

Dosage

• Beginner: 3 g (½ level teaspoon) per 150 L (40 US gallons), twice a week. Dissolve in at least 250 ml (1 cup) of soft water. Check alkalinity every 2 weeks.
• Advanced: Titrate until the alkalinity reaches 3–6 meq/L (8–17 dKH). Each 3 g dose per 150 L increases the alkalinity by 0.25 meq/L. Do not exceed 12 g per 150 L per day.
• Expert: determine the consumption rate and configure a continuous drip. Formula: m = 0.08 × v × a (m = grams, v = volume in liters, a = increase in meq/L).

Preparation for dosing pump

According to Seachem, 1 teaspoon of Reef Builder dissolves in 150 ml of liquid, which is equivalent to 33.3 g per liter of RO/DI water. It is normal for the pre-mixed solution to be slightly cloudy—add it to the tank after a few minutes of standing, and it will dissolve quickly. Small amounts of calcium carbonate (chalk) may form if the solution is left to stand overnight, but these will dissolve within the aquarium's volume.

Manufacturer's precautions

• Do not exceed 12 g per 150 L per day
• Excess alkalinity can accelerate the loss of calcium, magnesium, and strontium.
• Do not mix directly with a calcium, magnesium, or strontium supplement — alternate days or wait at least 30 minutes.

Available formats

• 50 g
• 300 g
• 600 g
• 1.2 kg
• 4 kg

Why choose the Reef Builder from ReefSolution?

For complete control of reef parameters, combine Seachem Reef Builder with Seachem Reef Advantage Calcium for calcium and Seachem Reef Buffer if pH also needs adjustment. The equivalent liquid version is Seachem Reef Carbonate. Monitor your parameters with the Salifert KH/Alk Test Kit or the Hanna Checker Alkalinity.

Frequently Asked Questions

What is the difference between the Reef Builder and the Reef Buffer?

The Reef Builder increases carbonate alkalinity without immediately affecting pH. The Reef Buffer increases both alkalinity and pH simultaneously thanks to its pK of 8.6. When pH is not a concern, use the Reef Builder. When pH is low, use the Reef Buffer.

What is the difference between Reef Builder and Reef Carbonate?

Reef Builder is the powdered version, and Reef Carbonate is the liquid version. Both produce the same end result. Reef Carbonate uses a slightly different salt blend to maximize concentration in liquid form.

Can the Reef Builder be used with a dosing pump?

Yes. Dissolve 33.3 g per liter of RO/DI water. The solution may be slightly cloudy, which is normal. Small amounts of calcium carbonate may form if the solution stands for a long time, but these will dissolve in the aquarium.