API Nitrate Test Kit Fresh/Saltwater
Water type
Freshwater + Marine
Number of tests
90 tests
API Nitrate Test Kit Fresh/Saltwater
Tracks the end product of the nitrogen cycle before it drives an algae bloom. The API Nitrate Test Kit measures nitrate (NO₃⁻) from 0 to 160 ppm in fresh or saltwater, using a liquid reagent test read against two colour charts – one for freshwater, one for saltwater. Each kit contains about 90 tests.
Key features
- 0–160 ppm range – covers everything from a healthy reading to a serious spike.
- Fresh and saltwater charts included – two separate colour cards, because the target reading differs by water type.
- About 90 tests per kit – works out to about 59c per test.
- 5 mL sample – small enough to test often without disturbing the tank.
- Two-reagent test – both bottles matter; under-shaking Bottle #2 is the most common cause of a false low reading.
How to use it
- Fill the supplied test tube to the 5 mL line with a water sample.
- Add 10 drops from Bottle #1 and invert the tube several times to mix.
- Shake Bottle #2 vigorously for at least 30 seconds before opening it – API states this step is extremely important, since the nitrate reagent settles and under-reads if it isn't shaken hard enough.
- Add 10 drops from Bottle #2, then shake the closed tube vigorously for a full minute.
- Wait 5 minutes for the colour to develop.
- Compare against the matching colour card – freshwater or saltwater – for your tank.
Specifications
| Brand | API (Mars Fishcare) |
|---|---|
| Measures | Nitrate (NO₃⁻) |
| Range | 0 to 160 ppm (mg/L) |
| Resolution | Not published by API |
| Sample size | 5 mL |
| Time to result | 5 minutes |
| Water type | Freshwater and saltwater (two colour charts included) |
| Tests per kit | Approximately 90 – see note below |
| Freight | Standard |
API's own product page does not state a tests-per-kit figure. The ~90 figure above is consistent across several independent retailers who reproduce the count printed on API's packaging; treat it as a close approximation rather than a guaranteed count.
What's included / what you'll still need
Included:
- Bottle #1 and Bottle #2 reagent solutions
- Glass test tube
- Freshwater colour card
- Saltwater colour card
- Instruction booklet
Not included:
- A reference or calibration standard
- Any product for correcting a high reading
Target ranges
| Setup | Target nitrate |
|---|---|
| Freshwater community | 40 ppm or below – API's recommended ceiling |
| Marine and reef, especially with invertebrates | As low as practically achievable |
API does not publish a single numeric marine target; it advises keeping nitrate as low as possible where invertebrates are kept, since they're markedly more sensitive to nitrate than fish.
When the reading is out of range
A rising nitrate reading is usually a water-change signal rather than an emergency, but a stubborn or climbing number is worth acting on before it turns into algae. API Nitra-Zorb is rated by API to remove nitrate, alongside ammonia and nitrite, from freshwater between water changes. Increasing water change frequency and reducing feeding are the other two levers, and neither needs a product.
Suitable for, and not suitable for
Suitable for:
- Freshwater and marine fish-only and reef systems
- Routine weekly-to-fortnightly monitoring
- Diagnosing an algae outbreak or general water-quality check
Not suitable for:
- Replacing an ammonia or nitrite test – nitrate is the end product of the nitrogen cycle, not the early warning sign
- A newly cycling tank on its own – pair it with an ammonia and nitrite kit, or the Freshwater Master kit, while the tank is establishing
Safety and handling
- Avoid skin and eye contact with either reagent.
- Keep both reagent bottles out of reach of children.
- Rinse the test tube between uses so old reagent doesn't skew the next reading.
Goes well with
- API Freshwater Master Multi Test Kit 5 in 1 – ammonia, nitrite, nitrate, pH and high-range pH in one kit.
- API Ammonia Test Kit Fresh/Saltwater – the parameter to watch alongside nitrate in a newer tank.
- API Nitra-Zorb (210L) – the product to run when your nitrate reading comes back high.
Warranty and delivery
This is a consumable test kit, so no manufacturer warranty period applies. That does not affect your rights under the Australian Consumer Law: if the product is faulty, unsafe or not as described, you are entitled to a remedy.
Ships as standard freight.
Common questions
What's a safe nitrate level for my tank?
API recommends 40 ppm or below for a freshwater community tank. Marine and reef tanks, especially with invertebrates, should be kept much lower – as close to zero as practically achievable.
Why does the kit include two colour charts?
Fresh and saltwater develop the test colour slightly differently, so API supplies a separate chart calibrated for each water type. Always read against the chart that matches your tank.
Why did my reading come out lower than I expected?
The most common cause is under-shaking Bottle #2. API states the 30-second shake before opening the bottle, and the full minute of shaking after adding it, are both extremely important steps – the reagent settles and under-reads without them.
How many tests will one kit give me?
Around 90, based on the count printed on API's packaging as reproduced by several independent retailers. API's own website doesn't state a figure, so treat this as an approximation.
Can this kit test ammonia or nitrite too?
No, this kit measures nitrate only. Pair it with API's Ammonia and Nitrite kits, or the Freshwater Master Multi Test Kit, to cover the full nitrogen cycle.
What do I do if my nitrate keeps climbing?
Increase water change frequency, check you're not overfeeding, and consider a nitrate-reducing filter media such as API Nitra-Zorb between changes.
