Seachem MultiTest Phosphate

Seachem MultiTest Phosphate measures inorganic phosphate down to less than 0.05 mg/L, with 75 tests in the box. Phosphate is the nutrient most responsible for nuisance algae in both freshwater and saltwater tanks, so keeping an eye on it is one of the simplest ways to stay ahead of an outbreak. It works alongside the rest of our water testing gear and water care.

Why Test Phosphate

• It feeds nuisance algae. Hair algae, cyanobacteria, and diatoms all thrive on phosphate. When it climbs, an algae problem usually follows.
• It slows coral growth. In a reef, elevated phosphate interferes with calcification, so SPS and LPS keepers keep it very low.
• It sneaks in from everywhere. Fish food, tap water, and decaying matter all add phosphate. Testing tells you whether the source is your water or your husbandry.
• Planted tanks want a little. Live plants use phosphate as a nutrient, so freshwater aquascapers aim for a small, steady level rather than zero.

Specifications

Recommended Pairings

• Seachem PhosGuard, pull phosphate and silicate back down when your test reads high.
• Seachem MultiTest Reef Special, add silicate and iodide testing to phosphate for a full reef nutrient panel.

FAQ

What phosphate level should I aim for?
In a reef, keep it very low but not zero, since corals still need a trace. In a planted freshwater tank, a small measurable amount is fine and even helpful. In a fish only tank, lower is better to limit algae.

How do I bring phosphate down?
Run a phosphate remover like PhosGuard, do water changes with low phosphate water, and cut back on feeding and any decaying material.

Does it measure organic phosphate too?
This kit reads inorganic phosphate, the form that fuels algae and that removers target. It is the number most keepers act on.

Can I use it in both fresh and saltwater?
Yes, it is accurate in freshwater and marine aquariums alike.