Reef Builder 1.2 kg — KH Alkalinity Without pH Impact | Seachem

Seachem Reef Builder in a 1.2 kg format is a powdered alkalinity supplement that increases carbonate hardness (KH) with minimal and gradual impact on pH. With long-term use, the pH stabilizes at 8.3. Its blend of carbonate sources does not deplete calcium, magnesium, or strontium, unlike competing products based solely on sodium bicarbonate. The 1.2 kg format is the economical choice for aquarists who regularly dose alkalinity or use a dosing pump.

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.
• Economical 1.2 kg format for regular and automated dosing
• 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 changing the pH, and the Reef Buffer to increase both alkalinity and pH simultaneously. When pH is not a concern, the Reef Builder is the first choice for adjusting alkalinity.

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. The 1.2 kg format makes over 35 liters of concentrated solution. It is normal for the pre-mixed solution to be slightly cloudy—add it to the tank after a few minutes of resting. Small amounts of calcium carbonate may form if the solution is left to stand for too long, but these will dissolve within the aquarium 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?

The 1.2 kg format is ideal for aquarists who regularly use alkalinity supplements, especially SPS tanks with dosing pumps. Combine Seachem Reef Builder with Seachem Reef Advantage Calcium for calcium and Seachem Reef Buffer if pH adjustment is also necessary. 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

Is the 1.2 kg format advantageous for automated dosing?

Yes. The 1.2 kg format allows you to prepare more than 35 liters of concentrated solution for dosing pumps (33.3 g per liter of RO/DI water). Ideal for systems with high alkalinity consumption and daily dosing.

What is the difference between Reef Builder and Reef Carbonate?

Reef Builder is the powder version, while Reef Carbonate (4000 meq/L) is the liquid version. Both provide the same end result. The powder format is more economical for large volumes, while the liquid is easier to dose without pre-mixing.

Does Reef Builder affect the pH of the aquarium?

Not immediately. Reef Builder increases alkalinity with minimal impact on pH. With long-term use, the pH will tend to stabilize at 8.3. To raise the pH immediately, use Seachem Reef Buffer.