The Hanna Tester Hack Every Aquarist Needs to Know
The Hanna Tester Hack Every Aquarist Needs to Know
Hanna Instruments makes near-lab-grade digital colorimeters for reef and saltwater (SW) water testing, and once you understand their three basic test formats, every other Hanna test becomes easy to pick up. Here's a walkthrough of all three, using alkalinity, phosphate, and calcium as examples.
The Three Hanna Test Formats
Single-press: zero the tester on plain water, add reagent, press again for an instant reading (alkalinity)
Timed: add reagent, then press-and-hold to start a countdown timer (2–10 minutes depending on the test) before the reading appears (phosphate)
Multi-step: requires deionized water, precise syringe measurements, and multiple reagents added in sequence (calcium — the most involved of the three)
Key Technique Notes
Always fill syringes to the line at the bottom of the plunger, not the top — that's what gives an accurate reading
Rinse cuvettes with deionized water before each use, wipe the outside dry, and eliminate air bubbles by slow tilting before inserting into the tester
Powder reagent packets: shake contents to the bottom before opening along the cut line to avoid spilling
Calcium testing specifically requires deionized water (not RO water) for accurate results
Sample Readings From This Test
Alkalinity: 9.1 dKH (slightly high, but corals were doing well)
Phosphate: 0.4 ppm
Want lab-grade accuracy on your reef tank's parameters? Shop the Hanna Marine Alkalinity Checker and reagent refills at natureaquariums.com, or stop by our Lauderhill store — we carry single Hanna tests and can walk you through them in person.
