How much
How much salt for a 100 gallon?
Pre-calculated for the 100 gallon (60 × 18 × 20 in · raw volume ≈ 94 US gal · water volume ≈ 83 US gal).
By scenario
| Scenario | Amount |
|---|---|
| Initial fill (cycling the tank) | 27.3 lb (12375 g) Or about 1.50 × 7 kg buckets / 0.47 × 22 kg buckets. |
| 10% weekly water change | 2.74 lb (1245 g) 8.3 gal new saltwater. Many reefers settle here as a routine. |
| 20% bi-weekly water change | 5.48 lb (2490 g) 16.6 gal new saltwater every 2 weeks. |
| Annual salt budget (10% weekly) | 142 lb (64.7 kg) Plan on 10 × 7 kg buckets per year. |
Brands hobbyists actually use
Buckets reefers actually buy at this volume. Coral Pro for high-alk SPS, Pro Reef for low-alk dosing tanks, Reef Crystals for budget mixed reefs.
Red Sea Coral Pro Salt — 22 kg bucket (175 gal mix)
Best per-gallon value for SPS tanks.
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Tropic Marin Pro Reef Salt
7–8 dKH spec. The go-to for calcium-reactor and Triton tanks.
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Instant Ocean Reef Crystals — 200 gal box
Cheapest reef salt with decent reef chemistry. Used to start.
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