Alkalinity Supplement Calculator

Enter your aquarium details to calculate the amount of alkalinity supplement needed.

Total System Volume

Gallons Liters

Current Alkalinity Level

dKH PPM

Desired Alkalinity Level

dKH PPM

Product

Start slow: Start with half of the recommended dose, not the full amount all at once. Large alkalinity corrections can cause extreme changes in water chemistry. Use smaller amounts over 1 to 2 days or longer to make gradual changes. Monitor pH closely and avoid swings greater than ±0.20. Test your parameters daily until levels are back in line.

Start Slow: Recommended Dosage

Note: The values generated by this calculator are suggested starting points and should be adjusted based on your tank’s needs.

We recommend beginning with half the calculated dose and testing your alkalinity level 24 hours later. From there, adjust slowly as needed to reach your target.

Avoid dosing the full amount all at once. Sudden changes in alkalinity can destabilize water chemistry and stress corals. Instead, split the dose over 1–2 days or more for a safer, gradual correction.

Monitor pH closely during this process and avoid swings greater than ±0.20. Test your parameters daily until stability is achieved.

Keeping Alkalinity Stable

Keeping alkalinity stable is one of the most important parts of maintaining a healthy reef tank, but precision is key. This calculator helps you determine the appropriate dose based on your tank volume, current alkalinity level, target alkalinity level, and your preferred supplement brand.

How This Calculator Works

This tool is designed to help reef keepers dose accurately using trusted alkalinity products. By inputting your current and desired alkalinity levels, the calculator determines the amount of supplement needed based on your tank volume and the concentration of the product selected.

Supported Alkalinity Supplements

Red Sea Foundation B (Alk): A concentrated alkalinity supplement to support coral growth.
Brightwell Reef Code B: Liquid alkalinity supplement with balanced carbonate hardness.
Fauna Marin ELEMENTALS KH: Highly pure carbonate additive for precise alkalinity control.
Tropic Marin Balling Part B: Sodium bicarbonate-based alkalinity supplement for Balling systems.
Oceans Blend Part 2: An effective alkalinity solution for reef tanks with varying demands.
ESV B-Ionic Component No. 1 (Alk): Part of the B-Ionic two-part system for alkalinity maintenance.
Two Little Fishies C-Balance Part B: A two-part system designed to replicate natural seawater alkalinity ratios.
Seachem Reef Fusion Two: A combined calcium and alkalinity supplement.
Aquaforest Component 1+2+3: A multi-component system including alkalinity support.
Fritz RPM Pt. 1: A high-purity carbonate alkalinity buffer.

When to Dose Alkalinity

Most reef tanks aim for an alkalinity range between 7–11 dKH (125–220 PPM). You should dose when your alkalinity levels drop below your target, especially in coral-heavy systems where consumption is high. Always test before and after dosing to confirm effectiveness.