Filter Media & Cleaning

API Phos-Zorb

Freshwater & marineAlgae control

API Phos-Zorb is a chemical filtration pouch that adsorbs phosphate and silicate from aquarium water. Both arrive with tap water and food and both feed algae; silicate is also what brown diatom films grow on. Removing them clears the murkiness they cause, starves nuisance algae, and takes out compounds that hold back plant growth. One pouch treats up to 210 litres in freshwater or saltwater. Rinse it for several minutes under the tap to activate it, set it in the filter flow, and replace it every two months or whenever a phosphate or silicate test shows a reading.

View at Jungle Aquatics

Live pricing and stock on jungleaquatics.com — purchase through Jungle Aquatics, with delivery across South Africa.

Dosage calculator

Enter your aquarium volume and the calculator works out how much API Phos-Zorb to use for each rate on the pack.

Aquarium volume

Measured in

Use the water the tank actually holds, less substrate and decor.

Pouches needed1 pouches per 210 litres
Enter a volumeReplace every 2 months, or when phosphate is detected

Rinse under the tap for several minutes to activate the media before use.

A guide only — always follow the dosing instructions printed on the pack, and measure with the bottle's cap or a syringe rather than by eye.

Technical details

Product type	Chemical filtration pouch — phosphate and silicate remover
Treats	Up to 210 litres per pouch
Removes	Phosphate, silicate, compounds that inhibit plant growth
Suitable for	Freshwater and saltwater aquariums
Lasts	About 2 months, or until phosphate or silicate is detected
Rechargeable	No — replace
Preparation	Rinse under the tap for several minutes to activate
Made by	Mars Fishcare, USA

Will Phos-Zorb starve my live plants?

Plants need a little phosphate, so in a densely planted tank use it with a test kit rather than permanently. Run a pouch when the Phosphate Test Kit reads high or algae is taking hold, and take it out once the reading drops and the algae recedes; API notes the pouch also removes compounds that inhibit plant growth, so moderate use tends to help plants rather than hurt them. In fish-only, goldfish, cichlid and marine tanks it can run continuously, changed every two months. Each pouch treats up to 210 litres; a large tank takes two.

Starve the algae of phosphate

Algae cannot grow without phosphate, and most tanks with a persistent algae problem test high for it. Phos-Zorb pulls phosphate out of the water column continuously, so whatever comes in with food and water is removed before algae can use it. Used with the Phosphate Test Kit, it turns algae control into a number you can watch fall.

Silicate and the brown diatom film

The brown dusting that covers glass and substrate in a new tank is diatoms, and they build their shells from silicate. Phos-Zorb removes silicate as well as phosphate, which is why it clears diatom blooms that carbon and water changes leave untouched.

Fresh, salt and reef

Reef keepers use phosphate removers constantly because phosphate stops stony corals calcifying. Phos-Zorb works in fresh and salt water alike; in a reef, test phosphate weekly and change the pouch when a reading returns rather than on a fixed schedule.

Frequently asked questions

Can I use Phos-Zorb in a reef tank?

Yes. It removes phosphate and silicate in saltwater, which is standard practice in reef keeping to protect coral growth.

How do I know when to replace it?

Every two months as a rule, or sooner if a phosphate or silicate test shows a reading while the pouch is in the filter.

Does it help with the brown algae in a new tank?

Yes. That brown film is diatoms, which need silicate; Phos-Zorb removes silicate and starves them.

Why rinse it for several minutes?

Rinsing removes dust and activates the media. Run it under the tap until the water clears before placing it in the filter.

Is API Phos-Zorb available in South Africa?

Yes — Jungle Aquatics in Fourways, Johannesburg stocks it and delivers nationwide; live pricing and stock are on jungleaquatics.com.

Stocked & supported by Jungle Aquatics

South Africa's leading pet and aquarium store since 2007 — with the API range on the floor in Fourways, advice from people who test water every day, and easy ordering from anywhere in the country.

Visit or contact the store Shop online →