Methods

Reef tank parameter targets by brand, side by side

Alkalinity, calcium, magnesium, nitrate, phosphate and potassium targets as each brand and guide publishes them, with the year and the source. Published alkalinity alone runs from 6.5 to 12.6 dKH. Here is why, and what to do about it.

Last checked 21 October 2026. How we check

What targets does each brand publish?

A dash means the source does not publish that figure on the pages we could open. Rows marked typical, check were read in a retailer copy or search summary, not on the brand's own page. Natural seawater sits at about 6.7 dKH, says Triton's FAQ.

Why do the published targets differ?

• The way you dose. Red Sea runs alkalinity high, up to about 12 dKH, and argues that raised, balanced calcium, alkalinity and magnesium speed growth. Triton, Fauna Marin and Zeovit stay near natural seawater. A method built around high alkalinity and one built around natural levels both work; mixing their numbers does not.
• The corals and the goal. Red Sea's 2024 manual gives different numbers for growth, balance and colour; low-nutrient SPS tanks aim lower on alkalinity and nutrients than soft coral tanks. Charterhouse gives soft coral tanks nitrate of 5 to 15 and SPS tanks 1 to 5.
• The salt. Salt brands mix to different alkalinity, so a water change pulls your tank towards your salt, not towards a brand target. Kraken suggests matching your target to your salt to avoid swings.
• The test kit. Hobby kits differ in resolution, and reagents drift as they age. ICP labs disagree with each other on several elements. A target finer than your kit can read is not a target you can hold.
• The year. Red Sea set targets by coral type in 2011, by tank type in 2021 and by objective in 2024. Always check the date.
• Nutrient fashion. Older advice wanted nitrate and phosphate near zero. Since about 2015 Fauna Marin, Triton, BRS and Reef Builders all warn that near-zero nutrients pale or starve corals.

Which numbers should I aim for?

If you follow a method, use its numbers. If you do not, this middle band sits inside most of the sources above and close to natural seawater. It is our reading, not a brand's.

How fast can I correct a parameter?

Red Sea caps daily rises at about 1.4 dKH (0.5 meq/L) of alkalinity, 20 ppm of calcium and 10 ppm of magnesium. Some SPS keepers prefer under 1 dKH a day (typical). Fix salinity first: Red Sea notes a 1 ppt rise lifts calcium by about 13 ppm and magnesium by about 40 ppm.

What units are these in?

Alkalinity in dKH. One meq/L is 2.8 dKH (Red Sea), and 1 dKH is 17.848 mg/L as calcium carbonate. Calcium, magnesium, nitrate, phosphate and potassium in ppm, which is the same as mg/L in seawater for these purposes. Some test kits report nitrate as nitrate-nitrogen or phosphate as phosphorus, which read lower; check the box. The unit converter switches between them.