Reviews · Test Kits
Hanna vs Salifert vs Red Sea — the test kit face-off, by published specs
Every "best test kit" list says accurate; almost none quotes an accuracy spec. The manufacturers publish these numbers — Hanna states ±0.3 dKH ±5%, Red Sea claims 0.14 dKH, Salifert publishes step resolution but no ± spec at all — and comparing them changes the answer. Here's each parameter, with the published specs, the true cost per test, and the failure modes owners actually report.
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Specs and prices from manufacturer and retailer pages on 2026-07-11 (each row links its source). Where a manufacturer publishes no accuracy spec, we say "not published" — we don't fill the gap with vibes. Full methodology →
The one-paragraph verdict
For alkalinity — the test you'll run 50 times a year — Hanna's objective digital readout justifies its ~$3/test cost, and it's the only alkalinity option with a full published ± spec. For everything else, Salifert's titrations at $0.19–0.44/test are the value play the hobby quietly standardized on, if you can live with judging a color endpoint. Red Sea's Pro kits sit between: tighter claimed specs than Salifert, bigger kits, but the same human-judged endpoint and the most owner complaints about reading it.
Alkalinity
The one to test weekly — it moves fastest and corals feel it first.
| Kit | Published accuracy | Resolution | Method | Cost/test | Price |
|---|---|---|---|---|---|
| Hanna HI772 Marine Alkalinity Checker 25 tests · refill $18.99 | ±0.3 dKH ±5% of reading | 0.1 dKH | digital colorimeter | $3.00 | $74.99 ↗ |
| Salifert KH/Alk Profi-Test 100 tests | not published | 0.1 meq/L (~0.3 dKH) per titration step; double in high-res mode | titration (drop-count, color endpoint) | $0.19 | $18.79 ↗ |
| Red Sea KH/Alkalinity Pro 75 tests · refill $28.99 | 0.05 meq/L (0.14 dKH) | not published | titration (syringe, color endpoint) | $0.60 | $44.99 ↗ |
Calcium
Moves slowly; every 1–2 weeks is plenty for most tanks.
| Kit | Published accuracy | Resolution | Method | Cost/test | Price |
|---|---|---|---|---|---|
| Hanna HI758 Marine Calcium Checker 25 tests · refill $34.99 | ±6 ppm ±5% of reading | 1 ppm | digital colorimeter | $3.00 | $74.99 ↗ |
| Salifert Calcium Profi-Test 50 tests | not published | 5 mg/L per titration step | titration (drop-count, pink→blue endpoint) | $0.44 | $21.79 ↗ |
| Red Sea Calcium Pro 75 tests · refill $28.99 | 5 ppm | not published | titration (syringe, color endpoint) | $0.60 | $44.99 ↗ |
Magnesium
The stabilizer — check every few weeks, or when Alk/Ca act strange.
| Kit | Published accuracy | Resolution | Method | Cost/test | Price |
|---|---|---|---|---|---|
| Hanna HI783 Marine Magnesium Checker 25 tests · refill $25.99 | ±5% of reading | 5 ppm | digital colorimeter | $3.00 | $74.99 ↗ |
| Salifert Magnesium Profi-Test 50 tests | not published | 30 mg/L per titration step | titration (drop-count, grey/blue endpoint) | $0.44 | $21.99 ↗ |
| Red Sea Magnesium Pro 100 tests · refill $28.99 | 20 ppm (Red Sea's page; BRS's listing says ±10 ppm — we report the manufacturer's own number) | not published | titration (syringe, color endpoint) | $0.45 | $44.99 ↗ |
Phosphate
The algae budget. Low numbers need real resolution to be meaningful.
| Kit | Published accuracy | Resolution | Method | Cost/test | Price |
|---|---|---|---|---|---|
| Hanna HI774 Phosphate ULR Checker 10 tests · refill $18.99 | ±0.02 ppm ±5% of reading | 0.01 ppm | digital colorimeter | $7.50 | $74.99 ↗ |
| Salifert Phosphate Profi-Test 60 tests | not published | not published | visual comparator card | $0.37 | $21.99 ↗ |
| Red Sea Phosphate Pro 100 tests · refill $34.99 | ±0.02 ppm | not published | visual comparator card | $0.58 | $57.99 ↗ |
Nitrate
The other nutrient — modern reefs run it low but not zero.
| Kit | Published accuracy | Resolution | Method | Cost/test | Price |
|---|---|---|---|---|---|
| Hanna HI781 Marine Nitrate LR Checker 25 tests · refill $24.99 | ±0.25 ppm ±2% of reading (0-5 ppm direct; to 50 ppm via dilution) | 0.01 ppm | digital colorimeter | $3.00 | $74.99 ↗ |
| Salifert Nitrate Profi-Test 60 tests | not published | not published | visual comparator card | $0.33 | $19.79 ↗ |
| Red Sea Nitrate Pro 100 tests · refill $34.99 | ±0.125 ppm (BRS listing) | not published | visual comparator card | $0.58 | $57.99 ↗ |
Cost per test = kit price ÷ tests per kit, computed only where the manufacturer publishes a test count. "Not published" means exactly that — Salifert documents titration step size but no ± accuracy; treat step size as a floor on uncertainty, not a substitute for it. Salifert phosphate reports PO4-P (phosphorus), not phosphate ion — ×3.066 to compare across brands.
The catch column, spelled out
Hanna: the cuvette technique matters — owners recommend syringe-measuring the sample rather than trusting the fill line, and the phosphate checker's reagent-powder handling is the classic source of user error. The calcium and nitrate checkers are multi-step; the alkalinity checker is the easy one.
Salifert: the color endpoint is genuinely subjective — owner threads document ~0.4 dKH spread between readers of the same titration. Test counts are honest but consumption scales with your levels.
Red Sea: the endpoint drifts in over ~5 drops, which is the most-complained-about readability in the category; the magnesium refill holds fewer tests than the original kit, so the refill economics are worse than the sticker suggests.
FAQ
Which parameter should I test most often?
Alkalinity. It drives coral skeletal growth, buffers pH, and moves faster than anything else you track — the standard advice is to test daily while dialing in dosing (until it holds within ~0.3 dKH for three straight days), then weekly. Calcium and magnesium drift slowly and can run on a 1–2 week cadence.
Digital (Hanna) or titration (Salifert / Red Sea)?
The real difference is who judges the endpoint. Hanna's checkers read the color with an LED and photocell — objective, repeatable, and roughly 5–10× the cost per test. Salifert and Red Sea end on a human-judged color change, which is the single most repeated complaint across owner forums: two careful people can read the same titration ~0.4 dKH apart. A common setup: Hanna for alkalinity (the high-frequency, precision-sensitive test), Salifert for everything else.
Why do two kits disagree on the same water?
Partly endpoint subjectivity, partly units: Salifert's phosphate kit reports phosphorus (PO4-P), not phosphate ion — multiply by ~3.066 before comparing it to a Hanna or Red Sea reading. Owner threads describing "wildly different readings" between brands are usually one or both of these. When kits disagree and it matters, an ICP lab test ($30–50, every few months) is the tiebreaker.
Do ICP tests replace test kits?
No — they complement them. ICP labs measure trace elements your kits can't and validate your kits' accuracy, but a 1–2 week mail turnaround can't catch an alkalinity swing that stresses coral in 48 hours. ICP quarterly, alkalinity weekly.
Reading high nitrate or phosphate? The water change calculator turns the number into a plan, and the carbon dosing guide covers export when dilution isn't enough. Dosing to targets: the dosing calculator.
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