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Free Reef Aquarium Calculators
Free Reef Aquarium Calculators — 15 Professional Tools for Marine Aquarists
Maintaining a healthy reef tank requires precise water chemistry. Whether you need to raise calcium, dial in alkalinity, calculate a Balling method recipe, or size a heater for a new build — our free professional calculators give instant, accurate answers. Built specifically for saltwater and reef aquariums. No sign-up required.
ICP Analysis Tool
Paste your ICP lab results and instantly see which parameters are out of range with expert dosing advice.
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Dosing Calculator
Calculate exact ml doses for Brightwell Aquatics supplements based on your tank volume and current levels.
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Balling Method
Get precise CaCl2, NaHCO3 and salt recipe quantities by Hans-Werner Balling for any solution volume.
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Calcium Calculator
Find out exactly how many grams of calcium chloride to add to raise Ca to your target ppm.
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Magnesium Calculator
Calculate MgCl2 and MgSO4 needed to bring magnesium up to the ideal 1280-1400 mg/L range.
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KH / Alkalinity
Determine how much baking soda or washing soda raises KH to your target in dKH.
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Potassium Calculator
Calculate KCl dosage to raise potassium to optimal levels for SPS coral coloration.
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Tank Volume
Convert external glass dimensions (inches) to exact gallons — accounting for glass thickness and water level.
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Heater Power
Find the correct heater wattage for your tank size and room temperature differential.
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Flow Heater
Calculate watts needed to heat flowing water to a target temperature.
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Ventilation
Determine required CFM to cool your aquarium stand or sump cabinet.
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Water Changes
Model how water parameter levels evolve over multiple consecutive water change cycles.
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Substrate / Sand
How much aragonite sand or substrate do you need for a given depth in your tank?
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Glass Dimensions
Get a complete cut list for building a custom glass aquarium.
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Glass Thickness
Find the minimum safe glass or acrylic thickness for your tank dimensions.
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Frequently Asked Questions
Are these calculators free to use?
Yes — all 15 tools are completely free. No account, no subscription, no limits. They run entirely in your browser.
How accurate are the results?
Formulas are based on established marine chemistry (IUPAC molar masses, NSW reference values, Balling method by Hans-Werner Balling). Always dose gradually and re-test before adding more.
Which calculator should I start with?
If you have recent ICP test results, start with the ICP Analysis Tool — it flags every parameter that needs attention at once. If you need to raise a specific element, go directly to that calculator.
