🧂 Reef Salt Mix Calculator
Calculate the exact amount of salt mix needed for water changes or a new tank setup.
Amount of new saltwater to mix
Results
Salt Mix Needed
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Measure dry before adding to RO/DI water
Weight (oz)
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Weight
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Salinity / Volume
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Cups = Gallons × CupsPerGallon × SG adjustment
Weight: ~8.4 oz per cup of dry salt mix
Tip: Always add salt to water, never water to salt. Mix until fully dissolved and target SG reached.
Weight: ~8.4 oz per cup of dry salt mix
Tip: Always add salt to water, never water to salt. Mix until fully dissolved and target SG reached.
Mixing Saltwater for Your Reef
Proper salinity is critical for marine life. Most reef keepers target a specific gravity of 1.025 (35 ppt), while fish-only systems can run slightly lower at 1.023.
Best Practices
- Always use RO/DI water — never tap water
- Add salt to water, never water to dry salt
- Mix with a powerhead for 12-24 hours before use
- Verify SG with a refractometer, not a hydrometer
- Match temperature before adding to display tank
Salt Brand Comparison
Elevated-chemistry salts like Red Sea Coral Pro, Fritz RPM, and Tropic Marin Pro contain higher calcium, alkalinity, and magnesium — ideal for SPS-heavy tanks. Standard salts like Instant Ocean are perfect for FOWLR and soft coral tanks.