Disclaimer

The headline

reefcalcs is reference information, not advice. By using the Site you agree that:

• You are responsible for the decisions you make about your tank
• You will verify every number against your own test kit and a primary source before acting
• You assume all risk of livestock loss, equipment failure, property damage, and electrical or structural incident
• reefcalcs and its operator are not liable for outcomes — see the Terms of Use for the formal limitation

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 any of the following, and use of the Site does not establish any professional relationship:

• Not veterinary advice. We are not licensed veterinarians or aquatic-animal health professionals. If a fish or coral is sick, consult a vet who treats aquatic animals — many universities run aquatic medicine programs.
• Not structural engineering. The aquarium weight, glass thickness, and floor-load outputs are hobbyist estimates. For tanks over 75 gallons in residential settings, or any custom build, consult a licensed structural engineer.
• Not electrical engineering. Heater wattage, pump sizing, and lighting recommendations do not address circuit loading, GFCI requirements, or local electrical code. Consult a licensed electrician for any installation.
• Not financial advice. Affiliate product picks are suggestions, not financial recommendations.
• Not a substitute for testing. Every dosing output depends on your test-kit accuracy. Treat the calculator output as a starting estimate, then verify with a re-test 24 hours later before continuing.

Verify before you act

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.

Treatment and medication warning

The troubleshooting pages reference hobby treatments — fluconazole (Reef Flux), Bayer dip, peroxide, Chemiclean, and others — that are off-label uses of compounds developed for other purposes. Dosing these incorrectly can crash a tank in hours. Always confirm your diagnosis, read the manufacturer's full instructions, and dose the smallest amount that has been shown effective. reefcalcs is not a substitute for a vet.

Structural, electrical, and property risk

Aquariums weigh roughly 10 lb per gallon when filled. A standard 75-gallon tank with stand exceeds the residential live-load design figure (40 lb/sq ft) for many floor framings. For tanks over 75 US gallons in residential settings, verify floor loading against the building's engineering rating before installation.

The glass thickness calculator uses the Wisner hobby formula with a 3.8 safety factor — community standard but not peer reviewed. No calculator can substitute for a tank built and warranted by a competent fabricator. The aquarium weight calculator gives a starting estimate, not a structural engineering opinion.

Heaters fail. Use a redundant pair, wired through an external controller with an independent temperature probe, on a circuit protected by GFCI. Never rely on a heater's internal thermostat alone.

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, indirect, incidental, consequential, or punitive damages — including but not limited to livestock loss, tank failure, property damage, or commercial loss — arising from the use of this Site. The full limitation of liability language is in the Terms of Use.

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.

If a number looks wrong

Do not act on it. Email us with the citation that contradicts the current page and we will correct it. Livestock and property are not the right thing to roll the dice on.