Dose Your Alkalinity Correction
Enter your current and target KH and we'll work out how much to dose – based on Red Sea Reef Foundation B's published rate, split safely across days if the correction is a big one.
Based on Red Sea Reef Foundation B's published rate: 1 mL per 100 L raises alkalinity by 0.1 dKH. Dosing a different alkalinity product? Check its own label – dosing strength varies by brand.
FAQ
How much should I dose to raise my alkalinity?
Test your current KH first, then use the calculator above – it's built on Red Sea Reef Foundation B's stated rate of 1 mL per 100 L for every 0.1 dKH you need to raise. If you're dosing a different brand, check that product's own label; strengths vary.
Why can't I just dose the whole correction in one go?
A fast alkalinity swing is one of the more common ways reef keepers stress or lose corals, even when the destination number is perfectly reasonable. Spreading a larger correction over a few days, and re-testing before each dose, gets you there without the swing.
What KH should I be targeting?
Most reef tanks run somewhere between about 7 and 11 dKH, with SPS-dominant systems often kept a little lower and more stable (around 7–9 dKH) and mixed reefs a touch higher. Consistency matters more than the exact number – pick a target in a sensible range and hold it steady rather than chasing a "perfect" figure.
Do I need to dose calcium and magnesium at the same time?
Yes, ideally. Alkalinity, calcium and magnesium move together in a reef tank – correcting one in isolation, repeatedly, tends to pull the other two out of balance. Test and dose all three against their own results, and see our Calcium and Magnesium dosing calculators.
Shop Alkalinity Supplements
Dosing rate above is Red Sea Foundation B's published figure. Using Reef Fusion or another brand? Check its own label before dosing – rates differ.