How to Read Your Reef Tank Test Results

Test kits are only useful if you know what the numbers mean. At Tropical Treasures in Cheyenne, we love when customers test their water — but we get just as many questions about how to read the results. Here's a friendly cheat sheet for the parameters that matter most in a reef tank.

The big three for corals 🪨

Calcium (around 400-450 ppm), alkalinity (about 8-9 dKH), and magnesium (roughly 1300-1400 ppm) work together to build coral skeletons. They're linked, so keep them balanced and stable rather than chasing one in isolation.

Nitrate and phosphate 🧪

These are your nutrient levels. Aim for low but not zero — nitrate around 5-10 ppm and phosphate around 0.03-0.10 ppm is a healthy range for most reefs. Zero on both can actually starve corals and trigger nuisance algae like dinos.

pH, salinity, and temperature 🌡️

Target pH around 7.9-8.4, salinity near 1.025, and a stable temperature about 76-80°F. With all of these, stability matters more than hitting an exact number. Track trends over time, not single readings.

Tips for accurate testing ✅

Test at the same time of day, follow kit instructions exactly, replace expired reagents, and log your results so you can spot trends. A refractometer beats a swing-arm hydrometer for salinity. Need a reliable test kit? Browse our test kits and supplies or call 307-369-1118 and we'll point you to a good one.

What if a number looks off? 🤔

Don't panic or make big swings. Re-test to confirm, then correct slowly — small, gradual changes are always safer for corals than a sudden fix. When in doubt, bring us a water sample.

The bottom line 📊

Reading your test results is all about knowing the healthy ranges, watching trends, and making slow, steady corrections. Test regularly and your reef will thank you. Have results you're not sure about? Stop by Tropical Treasures in Cheyenne or call 307-369-1118, and find more reef tips on The Tank Buddy Blog.