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Saltwater Aquarium Guide Reef-keeping magazine
Water Chemistry

Alkalinity Dosing: Two-Part, Kalkwasser, and Stability Strategy

How to dose alkalinity for stable reef chemistry — daily test cadence, calculator math, and which method fits your tank.

By Saltwater Aquarium Guide Published

Close-up of the ridged surface of a stony brain coral
Photo: David Clode / Unsplash
In this article
  1. Two-part (BRS Pharma)
  2. Kalkwasser
  3. Calcium reactor

Alkalinity is the single most important parameter for SPS color and growth. Drift over 0.2 dKH/day will brown out colonies. Here are the three proven dosing methods.

Two-part (BRS Pharma)

Most flexible. Dose alkalinity, calcium, and magnesium independently. Best for mixed reefs.

Kalkwasser

Cheapest. Saturated calcium hydroxide solution dripped via ATO. Raises pH as a bonus.

Calcium reactor

Set-and-forget. Best for SPS-dominant tanks consuming >1 dKH/day.

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