Demo Reef Log

Log a New Reading

Recent Readings

↑ Import CSV ↓ Download CSV

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

2026-09-28

8.30

420

1310

1.025

78.4

8.22

8.0

0.11

0.00

340

✎

MANUAL

2026-09-27

8.30

417

1310

1.025

78.1

8.20

7.6

0.10

0.00

359

✎

MANUAL

2026-09-26

8.20

418

1314

1.025

78.3

8.21

7.7

0.10

0.00

363

✎

Preferred Ranges

Parameter	Target Range	Tolerable Range	Natural Ocean	Unit	Notes
Alkalinity dKH	7.0–11.0	6.0–12.0 dKH	~6.5 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⁺	400–550	370–600 ppm	~420 ppm	ppm	🦴Calcium is literally what coral skeletons are made of. Randy Holmes-Farley's range is 400-550 ppm, and natural seawater sits around 420. Low calcium slows growth; far above the range, the chemistry gets harder to keep balanced.
Magnesium Mg²⁺	1250–1400	1200–1450 ppm	~1280 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	1.025–1.027	1.023–1.028 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	76.0–82.0	74.0–84.0 °F	variable	°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	7.8–8.55	7.6–8.65	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⁻	5.0–50.0	1.0–100.0 ppm	<0.1 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. Randy Holmes-Farley lets it float between 5 and 50 ppm, and warns that more problems come from lowering nitrate than from the level itself. Steady beats low.
Phosphate PO₄³⁻	0.06–0.3	0.02–0.5 ppm	~0.005 ppm	ppm	🎨Corals need tiny amounts of phosphate to look colorful. Zero phosphate = pale, stressed corals. Randy Holmes-Farley lets it float between about 0.06 and 0.3 ppm. Above that, bring it down slowly, over weeks, not days.
Nitrite NO₂⁻	0.0–0.2	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	0.0–0.0	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	250–400	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.

Target ranges reflect your settings; “Natural Ocean” is the reference seawater value. Customize in Settings