Water Conditioners & pH

API Stress Zyme+

Freshwater & marineLive bacteria

API Stress Zyme+ is a maintenance bacteria, not a start-up one. Each teaspoon carries more than 300 million live bacteria that digest the organic sludge that builds up in gravel, on decor and inside filters — the uneaten food and waste that would otherwise rot into ammonia and cloud the water. Dosed weekly at 5 ml per 38 litres, it keeps the biological filter active and the tank cleaner between water changes, which means less gravel vacuuming and fewer surprises on the test kit. It suits freshwater and saltwater aquariums alike. Sizes run from 30 ml to 473 ml.

Size: 30 ml

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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 Stress Zyme+ to use for each rate on the pack.

Aquarium volume

Measured in

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

Maintenance dose5 ml per 38 litres
Enter a volumeOnce a week

Dose the whole tank volume after the weekly water change.

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	Live bacterial cleaner, liquid
Sizes	30 ml · 118 ml · 237 ml · 473 ml
Dose	5 ml (one teaspoon) per 38 litres, weekly
Treats	30 ml → 227 litres · 118 ml → 870 litres · 237 ml → 1 779 litres · 473 ml → 3 558 litres
Bacteria count	Over 300 million live bacteria per teaspoon
Suitable for	Freshwater and saltwater aquariums
How often	Weekly, as part of routine maintenance
Made by	Mars Fishcare, USA

What is the difference between Stress Zyme+ and Quick Start?

They are different bacteria for different jobs. Quick Start contains nitrifying bacteria that convert ammonia and nitrite — the cultures a new or disturbed filter lacks — and is dosed at set-up and after filter changes. Stress Zyme+ contains sludge-digesting bacteria that break down organic waste in gravel and filters, and is dosed weekly at 5 ml per 38 litres as ongoing maintenance. A new tank benefits from both: Quick Start to get the cycle going, Stress Zyme+ each week afterwards to keep waste from accumulating. Neither replaces water changes or gravel cleaning; they make both easier.

Eats the sludge before it becomes ammonia

Every flake that is not eaten and every gram of waste ends up as organic sludge somewhere in the tank, and its breakdown is what drives ammonia and nitrate upward. The bacteria in Stress Zyme+ consume that material directly, so there is less of it to foul the gravel, block the filter sponge and feed algae.

Keeps the biological filter working

A filter is only as good as the bacteria living in it. A weekly dose tops the colony up, helping it recover from water changes, medication and the inevitable filter rinse, and keeps the nitrogen cycle running steadily instead of lurching between spikes.

Once a week, fresh or salt

The dose is one teaspoon — 5 ml — for every 38 litres, once a week, in freshwater or marine tanks. Add it after the weekly water change so the bacteria go into clean water. The 237 ml bottle treats 1 779 litres, which is about eight months of weekly dosing on a 200-litre tank.

Frequently asked questions

Can I use Stress Zyme+ in a marine tank?

Yes. It is labelled for both freshwater and saltwater aquariums at the same weekly dose.

Will it clear cloudy water?

It reduces the organic waste that causes a lot of cloudiness and helps the filter cope, but it is not an instant clarifier. For a quick clean-up of cloudy freshwater, use Accu-Clear and let Stress Zyme+ deal with the cause.

Do I still need to vacuum the gravel?

Yes, just less often. The bacteria digest sludge, but solid debris and the nitrate it leaves behind still need regular water changes and a gravel clean.

Is it safe with plants and shrimp?

It is a bacterial product with no chemicals that harm plants or invertebrates, and is routinely used in planted community tanks. Keep to the weekly dose.

Is API Stress Zyme+ available in South Africa?

Yes — Jungle Aquatics in Fourways, Johannesburg stocks all four sizes and delivers across South Africa; live pricing and stock are on jungleaquatics.com.

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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.

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