Coral Compass Pro · $3/month · what's included
Enter the numbers from your ICP-OES lab report. Each element is compared with reference seawater (scaled to your salinity), flagged low, OK, or high, and for the major dosable elements you get the grams of a reef-grade salt needed to bring it back, split so no day adds more than about 10% of the seawater level. Metals like copper, zinc, and nickel are flagged when they're far above natural levels so you know to retest and look for a source.
The math
Grams of salt = (target − measured) mg/L × liters ÷ element fraction ÷ 1,000
Element fractions: potassium in KCl 0.524, strontium in SrCl₂·6H₂O 0.329, boron in boric acid 0.175, iodine in KI 0.764, fluoride in NaF 0.452. Reference levels at 35 ppt: K 399, Sr 7.9, B 4.5, F 1.3, Br 67, Mg 1,284, Ca 412 mg/L; iodine about 0.06 mg/L.
Try it
Sample: 100 gal at 35 ppt, ICP shows low potassium, strontium and iodine and raised copper.
| Element | You (mg/L) | Seawater | Status | Correction |
|---|---|---|---|---|
| K | 360 | 399.00 | ok | – |
| Sr | 6.5 | 7.90 | low | 1.6 g SrCl2·6H2O over 2 day(s) |
| I | 0.03 | 0.06 | low | 0.015 g KI over 3 day(s) |
| B | 4.4 | 4.50 | ok | – |
| Cu | 0.012 | 2.5e-4 | high | Well above natural seawater: retest and look for a source |
Sources
- Millero et al. (2008), The composition of Standard Seawater and the definition of the Reference-Composition Salinity Scale, Deep-Sea Research I 55
- Iodine and trace metal levels: typical open-ocean surface values (iodine about 58 µg/kg; copper, zinc and nickel below 1 µg/kg)
- Metal flag levels (Cu 5, Zn 10, Ni 5, Al 20, Pb 2, Sn 2 µg/L) and the 10%-per-day step are Coral Compass's conservative choices, not published limits
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