Disclaimer

What reefcalcs is

reefcalcs is a reference tool. The calculators implement formulas drawn from primary sources — Randy Holmes-Farley's aquarium chemistry articles, Bulk Reef Supply's product documentation, Tropic Marin and Red Sea's published dose constants, Triton's CoreChem methodology, and peer-reviewed marine chemistry literature. Every number on this site traces to a citation listed on the page where it appears.

What reefcalcs is not

reefcalcs is not veterinary advice, not a substitute for testing your own water, and not a guarantee of livestock health. Reef and aquarium chemistry involves living animals; small mistakes compound. Before you act on a number this site gives you, verify it against:

• Your own test kit reading, taken with a calibrated instrument
• The current condition of your livestock
• The manufacturer's instructions for the product you are dosing
• A second source you trust, ideally the primary citation linked on the calculator page

Calculators are approximations

Every formula on this site is a simplification of underlying chemistry. The dosing calculators assume:

• Your test kit is calibrated and within its accuracy band (Hanna Checkers ±2 ppm Ca, Salifert ±0.5 dKH, etc.)
• Your tank is at a typical reef temperature (24–27 °C) and salinity (33–35 ppt)
• The product you are dosing matches the published recipe — homemade and rebrand variants may have different concentrations
• You are dosing in a tank that does not have an unusual carbonate buffer system (e.g., heavily kalk-dosed tanks, ULNS systems on Triton method)

If your system is significantly outside these assumptions, the numbers will be in the right ballpark but the exact figure may be off by 10–30%. Adjust based on a re-test 24 hours after dosing, not based on a single calculator output.

The honest single-dose warning

Single-dose corrections above 2 dKH alkalinity, 50 ppm calcium, or 100 ppm magnesium are risky regardless of what any calculator says. Coral tissue reacts to rate of change, not to absolute values. Split large corrections across multiple days. A tank running stable at 6 dKH is healthier than a tank yo-yoing between 8 and 10 dKH every week.

Substrate, glass, and structural calculators

The glass thickness calculator uses the Wisner hobby formula with a 3.8 safety factor. This is the convention used across the reef community, but no calculator can substitute for a tank built by a competent fabricator with documented engineering. For tanks over 75 gallons in residential settings, also verify your floor load against the building's structural rating — the aquarium weight calculator gives a starting estimate, not a structural engineering opinion.

No warranty

reefcalcs is provided as-is with no warranty of accuracy, fitness for purpose, or freedom from error. The operator is not liable for any direct or indirect damages — including but not limited to livestock loss, tank failure, or property damage — arising from the use of this site. If a number you read here looks wrong, do not act on it; email us with the citation that contradicts it and we will correct the page.

Errata and corrections

This site is reviewed on the date stamped at the top of every calculator and parameter page. If you find an error, the fastest way to a correction is to send the primary citation that contradicts the current page to hello@reefcalcs.com. We update with citations, not opinions.