| Date | dKH dKH | Ca²⁺ ppm | Mg²⁺ ppm | Sal sg | Temp APEX °F | pH APEX | NO₃⁻ ppm | PO₄³⁻ ppm | NO₂⁻ ppm | NH₃ ppm | ORP APEX mV | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
APEX 2026-08-14 | — | — | — | — | 78.4 | 8.22 | — | — | — | — | 340 | ✎ | ||||||||
Temperature78.4–78.4 °F Δ0.0 pH8.22–8.22 Δ0.00 ORP340–340 mV Δ0
| ||||||||||||||||||||
MANUAL 2026-08-13 | 8.3 | 423 | 1308 | 1.025 | 78.3 | 8.21 | 7.4 | 0.10 | 0.00 | 0.00 | 357 | ✎ | ||||||||
MANUAL 2026-08-12 | 8.3 | 418 | 1312 | 1.025 | 78.3 | 8.20 | 7.8 | 0.10 | 0.00 | 0.00 | 359 | ✎ | ||||||||
| Parameter | Target Range | Tolerable Range | Natural Ocean | Unit | Notes |
|---|---|---|---|---|---|
| Alkalinity dKH | 8.0–12.0 | 7.0–13.0 dKH | 7-8 dKH | dKH | 🧪This is the #1 parameter that kills corals when it swings. Think of it as the skeleton-building ingredient. Dose consistently and test every day if you have SPS. |
| Calcium Ca²⁺ | 380–450 | 350–500 ppm | ~400 ppm | ppm | 🦴Calcium is literally what coral skeletons are made of. 420-440 ppm is the sweet spot — not too low (slow growth) or too high (chemistry gets weird). |
| Magnesium Mg²⁺ | 1200–1400 | 1150–1450 ppm | ~1285 ppm | ppm | 🔗Magnesium is the chemistry glue — it keeps calcium and alkalinity from fighting each other. Low mag = parameters that won't stay stable no matter what you dose. |
| Salinity | 1.025–1.026 | 1.022–1.028 sg | 1.025-1.027 | sg | 🧂Match the real ocean exactly — 1.025 SG. Your fish evolved for this. Even small swings stress them out. An ATO keeps it rock steady. |
| Temperature | 75.9–80.0 | 74.0–82.0 °F | 77-84°F | °F | 🌡️Keep it like a warm beach day — 78°F is the sweet spot. Too cold and fish get sluggish. Too hot and oxygen drops fast. |
| pH | 8.1–8.3 | 7.8–8.4 | 8.0-8.3 | ⚗️The ocean is slightly basic, and your tank should be too. pH naturally drops at night — open a window or run a refugium on a reverse cycle to keep it up. | |
| Nitrate NO₃⁻ | 2.0–10.0 | 1.0–30.0 ppm | ~0.01-0.05 ppm | ppm | 🌿A little nitrate is actually good — corals need it as food. Zero is a problem, not a win: it starves corals of color and, when phosphate stays up, invites dinoflagellates. Aim for 5-10 ppm; above 30 ppm nuisance algae takes over. |
| Phosphate PO₄³⁻ | 0.03–0.1 | 0.01–0.2 ppm | ~0.03 ppm | ppm | 🎨Corals need tiny amounts of phosphate to look colorful. Zero phosphate = pale, stressed corals. Too much = algae takeover. 0.05-0.08 ppm is the sweet spot. |
| Nitrite NO₂⁻ | 0.0–0.1 | 0.0–0.5 ppm | ~0 ppm | ppm | ⚠️Nitrite is the middle step in the nitrogen cycle. In saltwater it's far less dangerous than in freshwater — seawater's chloride blocks it at the gill — so treat it as a cycling telltale, not a toxin. A trace reading is usually test-kit noise. A real, sustained rise means your cycle isn't finished or something died. |
| Ammonia NH₃ | 0.0–0.02 | 0.0–0.1 ppm | ~0 ppm | ppm | ☠️The most dangerous parameter. Even 0.25 ppm can kill fish within hours. Zero always. If you see any ammonia in an established tank, do a water change immediately. |
| ORP | 250.0–430.0 | 200–450 mV | ~400 mV | mV | ⚡Oxidation reduction potential — a real-time proxy for water cleanliness. Healthy reef tanks sit 250–400 mV; lower hints at organic load building up (skimmer, GAC, water change). Probe drift is common; recalibrate quarterly. |
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