Salifert’s KH/Alk kit is the better pick if you want a repeatable alkalinity result for the least outlay and don’t mind doing a titration. The Hanna HI772 checker is better if you find color changes hard to judge or just want a number on a screen. Keep its reagents fresh, and know that its stated accuracy of ±0.3 dKH plus 5% of the reading is looser than its 0.1 dKH display suggests.
Both are standard tools in reef tanks. The bigger difference comes from how consistently you use them.
How do the Hanna HI772 and Salifert KH/Alk kit compare? #
| Hanna HI772 Checker | Salifert KH/Alk | |
|---|---|---|
| Method | Colorimeter: an LED reads the color of the treated sample | Titration: add reagent drop by drop until the color changes |
| Range | 0.0 to 20.0 dKH | Covers normal reef levels |
| Step size | 0.1 dKH on the display | 0.1 meq/L, about 0.3 dKH |
| Stated accuracy | ±0.3 dKH ±5% of reading at 25°C | Depends on your technique |
| Sample size | 10 ml | Small syringe sample |
| Consumables | Reagent packets, bought separately | Kit does 100 to 200 tests |
| Power | One AAA battery | None |
| You read | A number | A color change, by eye |
Specs for the HI772 come from Hanna Instruments. Salifert kits are sold for marine use. Hanna also markets the HI772 specifically for saltwater.
What does ±0.3 dKH ±5% of reading actually mean? #
It means the true value can sit a fair distance from what the screen shows. Add 0.3 dKH to 5% of the reading:
| Hanna shows | Possible true range |
|---|---|
| 7.0 dKH | 6.35 to 7.65 |
| 9.0 dKH | 8.25 to 9.75 |
| 11.0 dKH | 10.15 to 11.85 |
The 0.1 dKH display is resolution, not accuracy. A result of 8.7 tells you the meter’s best estimate, not that the tank is at 8.7 and not 8.8.
This matters less than it sounds. Most of the error in any hobby test is a steady offset. If your checker reads 0.4 dKH high every time, the trend is still right, and trends are what you act on. The Salifert kit has the same property. Its 0.3 dKH steps are coarse, but a careful titration repeats well, so a real drop of half a dKH shows up.
The real trouble starts when readings bounce between tests for reasons that have nothing to do with the tank.
Why do Hanna alkalinity readings drift? #
The common causes, most frequent first:
- Old or badly stored reagent. A frequent complaint on reef forums is readings that slowly sink as a batch of reagent ages, then jump back when a fresh pack is opened. Use reagents before their printed date and keep them away from heat and sunlight.
- Dirty or scratched cuvettes. Fingerprints, water spots and scratches all change how light passes through the glass. Hold cuvettes by the cap and wipe them with a lint-free cloth before every reading.
- Skipping the zero step with your own sample. The checker zeroes on untreated tank water first, then reads after the reagent. Zeroing on anything else throws the result off.
- Inconsistent timing or mixing. Follow the manual’s steps the same way every time.
If you doubt the meter itself, Hanna sells the HI772-11 calibration check set, with sealed standards at 0.0 and 5.0 dKH. It tells you whether the instrument is reading correctly, which separates meter problems from reagent problems.
What goes wrong with Salifert tests? #
Titration has its own failure points:
- Misjudging the endpoint. Stop at the first lasting color change, in good light, against a white background. Going one drop past it adds about 0.3 dKH of error.
- Air bubbles in the syringe. A bubble takes up volume the reagent should, which throws off the reading. Tap the syringe and push out bubbles before you start.
- Sloppy sample volume. Measure the tank water exactly as the instructions say.
- Tired eyes or color blindness. If you struggle to see the color change, the Hanna is the more practical tool.
Which one should you buy? #
| If you… | Get |
|---|---|
| Want the lowest cost per test and trust your eyes | Salifert |
| Find color endpoints hard to judge | Hanna HI772 |
| Test daily while dialing in dosing | Either, used the same way every time |
| Need to settle whether a reading is real | Both, so each can check the other |
| Share testing with family members | Hanna, because a number is harder to misread |
Costs change with retailer and region, so compare the price per test rather than the box price. The Hanna needs the meter plus reagent refills. The Salifert kit is a single purchase for 100 to 200 tests.
How do you cross-check two alkalinity kits? #
If you own both, or can borrow one from a club friend, a cross-check takes ten minutes:
- Take one sample of tank water in a clean cup.
- Run both tests from that same cup within a few minutes.
- Repeat each test once more.
- If each kit repeats itself within about 0.3 dKH but the two disagree, one has an offset. Check reagent dates first.
- If one kit won’t repeat itself, fix technique or replace reagent before trusting it.
Log which kit produced each result. In Fish Tank Tracker, every test has a notes field, so typing “Hanna” or “Salifert” beside the alkalinity reading means a sudden step on the chart has a known cause. The chart shades an 8 to 11 dKH band behind each reading, which makes a slow slide easy to spot before you reach for the dosing bottle. For the correction itself, see how to raise alkalinity in a reef tank with baking soda, and for test frequency, how often to test reef tank water.
Frequently asked questions #
Is the Hanna alkalinity checker more accurate than Salifert? #
Not necessarily. The Hanna shows finer steps, but its stated accuracy is ±0.3 dKH plus 5% of the reading, and reagent age can pull results lower. A careful Salifert titration is often just as repeatable, which is what matters for tracking trends.
How do I convert meq/L to dKH? #
Multiply meq/L by 2.8. So 3.0 meq/L is 8.4 dKH, and 0.1 meq/L, Salifert’s step size, is about 0.28 dKH. To go the other way, divide dKH by 2.8.
Why do my Hanna and Salifert results disagree? #
Usually one kit has a steady offset, most often from old reagent or a dirty cuvette on the Hanna, or endpoint judgment on the Salifert. Run both from the same sample twice. If the gap stays the same, pick one kit and stick with it for trend tracking.
Do Hanna checkers read phosphate the same way? #
Hanna’s phosphate checkers use the same colorimeter approach, but the ultra-low-range model reports phosphorus in ppb, not phosphate in ppm. Our guide to converting Hanna phosphorus ppb to phosphate has the conversion table.