Fluval Phosphate Test Kit 75 Tests
Water type
Freshwater + Marine
Part no.
A7872
Number of tests
75 tests
Fluval Phosphate Test Kit 75 Tests
A 75-test kit that tells you whether phosphate is fuelling your algae before you start guessing at fixes. The Fluval Phosphate Test Kit (Fluval part A7872) is a liquid reagent test reading 0.0–5.0 mg/L PO₄, suitable for both freshwater and marine aquariums.
Phosphate builds up from fish waste, uneaten food and decaying plant matter, and it's one of the two nutrients – alongside nitrate – that drive nuisance algae. This kit uses a colorimetric reaction: add the reagents to a water sample, wait two minutes, then match the colour against the included chart.
Key features
- 75 tests per kit – enough for weekly testing across well over a year in a single tank.
- 0.0–5.0 mg/L range – covers everything from a clean reef tank to a heavily stocked, overdue-for-a-water-change freshwater setup.
- Liquid reagent accuracy – a modified ascorbic acid colour reaction, generally more precise than dip-strip tests.
- Fresh and marine – one kit covers both water types, so it works across a mixed collection.
- Fast read – result in 2 minutes.
Specifications
| Spec | Detail |
|---|---|
| Manufacturer part number | A7872 |
| Number of tests | 75 |
| Range | 0.0–5.0 mg/L PO₄ |
| Method | Liquid reagent colour comparison |
| Time to result | 2 minutes |
| Water type | Freshwater and marine |
| Included | Reagent bottles, pipette, glass test tube, colour chart/instruction booklet |
What's included
Three reagent bottles, a pipette, a glass test tube and a printed colour chart with instructions. No reference/calibration solution is included – the colour chart is the reference.
Care and maintenance
Fluval's own guidance is to expect the best results within the first year after opening; reagents can lose accuracy with age and heat, so store the kit somewhere cool and out of direct sun and check the manufacture date if a reading looks implausible.
If your reading is high
A rising phosphate reading is usually addressed with a water change first, then ongoing chemical media if the source keeps coming back. Fluval's phosphate-removing filter pads are sized to the canister range: the 306/307/406/407 pack is the one to reach for on that filter series; the 106/206–107/207 and FX2/FX4/FX5/FX6 ranges use their own separate packs. Fluval ClearMax loose resin is the alternative for filters that use a media bag rather than a pad basket.
Suitable for, and not suitable for
Suitable for routine monitoring in freshwater, planted and marine/reef tanks. Not a nitrate, ammonia or pH test – those need their own kits, and phosphate alone won't diagnose an algae outbreak with more than one nutrient behind it.
Warranty and delivery
General Fluval warranty terms apply to any manufacturing defect, in addition to your rights under Australian Consumer Law. Standard parcel freight.
Common questions
What phosphate level should I be aiming for?
Fluval does not publish a single target figure for every tank type in this kit's documentation, so we're not going to invent one here – as a general rule, lower is better for algae control, and the trend over several tests matters more than any single reading. If you're chasing a specific target for a reef tank, a dedicated reef-focused test kit with finer resolution may suit you better.
Does this kit test for silicate as well?
No, this is a phosphate-only kit. Silicate needs a separate test.
How often should I test?
Weekly is a reasonable routine for a stable tank; test more often if you're actively treating a phosphate-driven algae problem or have just added new stock or a new light.
Can I use this on a nano or pico tank?
Yes – the sample size needed is small, so it works fine on nano setups.
