Brightwell Extrax Phos — spherical phosphate and silicate adsorption media

The Brightwell Extrax Phos is an advanced spherical adsorption media targeted at phosphate and silicate in marine, reef, and freshwater aquariums. Formulated in the United States by Brightwell Aquatics, its spherical shape maximizes reactive surface area and outperforms non-spherical alternatives on water contact time. The media never releases phosphate, silicate, or soluble compounds back into the system, unlike some low-grade GFO products.

Brightwell positions Extrax Phos as a nutrient-control program tool — usable ongoing on an active reef, or as a targeted cure when a phosphate spike threatens SPS coloration or the fight against nuisance algae.

What Extrax Phos is for and when to use it

Continuous reef PO₄ control — media reactor routine to hold PO₄ in the target range without daily intervention.
Cutting a phosphate spike — a tank leaving the "ugly stage" or recovering from a feeding imbalance, bringing PO₄ back to a healthy reef level.
Silicate control — young tanks whose source water still carries residual SiO₂ feeding diatoms.
Bulk format for large tanks — 600 g or 3.2 kg to match system size or multi-tank use.

Brightwell official use

Pre-rinse: rinse every 600 g of Extrax Phos in 1/2 US gal (1.9 L) of purified tap water and discard the water. Never rinse in saltwater — freshwater only.
Basic dose: 2 g of Extrax Phos per 1 US gal (3.8 L) of system volume.
Total capacity: 600 g adsorbs up to 20 mg/L of phosphate in 300 US gal (1,136 L).
Replacement: as soon as system PO₄ stops falling or starts rising — sign of complete media exhaustion.
Do not leave saturated media in place: it loses effectiveness without releasing what it holds, but a delayed swap extends the uncontrolled-PO₄ window.

Specifications

Brand: Brightwell Aquatics (made in the USA)
Available sizes: 300 g, 600 g, 3.2 kg
Type: spherical phosphate and silicate adsorption media
Capacity: 600 g adsorbs up to 20 mg/L PO₄ in 300 US gal
Compatibility: marine, reef, and freshwater aquariums
Safety: does not release adsorbed compounds back into water

Why choose Brightwell at ReefSolution

Brightwell Phosphat-E — the liquid phosphate remover to pair for a quick knock-down without waiting for a reactor install.
Brightwell MicroBacter7 — the bioculture that backs up biological PO₄ control alongside the media's chemical action.
Salifert Phosphate Test Kit — the 0.01 ppm test required to track Extrax Phos performance and catch exhaustion.

Frequently asked questions

How much Extrax Phos do I need for my tank?

The Brightwell baseline dose is 2 g per US gal (3.8 L) of system volume. For a 100 US gal (378 L) tank, initial media load is therefore 200 g. Brightwell-published capacity: 600 g adsorbs up to 20 mg/L PO₄ in 300 US gal — the total capacity before replacement.

Do I need to rinse Extrax Phos before use?

Yes, Brightwell recommends rinsing every 600 g in 1/2 US gal (1.9 L) of purified tap water before first use, and discarding the water. That rinse removes fine media dust. Brightwell explicitly states: never rinse in saltwater, freshwater only.

When do I know it's time to replace Extrax Phos?

Brightwell publishes a clear signal: as soon as system PO₄ stops falling or begins rising with the media still in place, capacity is fully exhausted. An accurate phosphate test (0.01 ppm) tracks that flip in real time — often a month between effective drawdown and saturation.

Can Extrax Phos be used in a freshwater aquarium?

Yes — Brightwell states the media is safe in marine and freshwater tanks. On a planted tank, Extrax Phos can trim PO₄ excess from an overdosed fertilizer or heavy feeding — provided you don't drop below the level plants require.