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Free Printable Reef Tank Parameter Log (PDF)

This is a free, one-page printable reef tank parameter log in PDF format. Each row is one test session: date, salinity (SG or ppt), pH, alkalinity (dKH), calcium (ppm), magnesium (ppm), nitrate (ppm), phosphate (ppm), and notes. Parameters rarely fail all at once — weekly testing with a written record lets you catch which value is drifting before it causes coral bleaching, RTN, or a livestock crash. Not veterinary advice.
Download the PDF — free No sign-up. No email. Print and go.

How to use this sheet

  1. Print the PDF and keep it near your test kit station.
  2. Run your parameter tests and log each value in the corresponding column — a full test session takes one row.
  3. In the Notes column, record any dosing you added after testing: two-part, kalkwasser, calcium reactor output, or carbon dosing.
  4. After a few weeks, scan the columns vertically — alkalinity is the most volatile and often the first to show a drift pattern.
  5. Bring the log to your local reef shop if you're troubleshooting a coral problem; a parameter trend is far more informative than a single test result.

Questions

Is this log really free?

Yes. The PDF is free to download and print — no sign-up, no email.

How often should I test a reef tank?

Most reef-keepers test alkalinity two to three times per week (it's consumed fastest), calcium and magnesium weekly, and nitrate and phosphate weekly to biweekly depending on livestock load. Salinity and pH can be monitored continuously with probes, but periodic manual verification is still useful for calibration checks.

What are the target ranges for reef parameters?

Common targets: salinity 1.025–1.026 SG, pH 8.1–8.3, alkalinity 8–9 dKH, calcium 400–450 ppm, magnesium 1250–1350 ppm, nitrate 1–10 ppm for mixed reefs, phosphate 0.02–0.05 ppm. Actual targets depend on your specific system and livestock.

Is there an app version?

Yes — Coralog for iPhone logs reef parameters, dosing, and livestock with trend charts and drift warnings. Core is free, no account needed, and your data stays on your device.

Want the log to analyze itself?

Coralog for iPhone tracks the same things in seconds and shows you the patterns — free core, no account, and everything stays on your device.

Download on theApp Store