Plant Care

API CO2 Booster

FreshwaterPlant safe

API CO2 Booster puts carbon into a planted aquarium in liquid form. Carbon is the raw material plants turn into new growth, and running short of it is one of the commonest reasons a planted tank stalls even under good light. The liquid supplies simple carbon compounds that release CO2 to plants gradually. It is the practical choice for a low-tech tank with no gas injection, and it can also run alongside a pressurised CO2 system as a supplement. Dose 1 ml per 40 litres every day: the 237 ml bottle treats about 8 900 litres, it is safe for freshwater fish, and it does not alter pH.

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Dosage calculator

Enter your aquarium volume and the calculator works out how much API CO2 Booster to use for each rate on the pack.

Aquarium volume

Measured in

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

Daily dose1 ml per 40 litres
Enter a volumeOnce a day

A 1 ml syringe makes the small daily doses easy to measure accurately.

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	Liquid carbon supplement
Sizes	237 ml
Dose	1 ml per 40 litres
How often	Daily
Treats	237 ml treats 8 900 litres
Key ingredient	Simple carbon compounds that slowly release CO2
Suitable for	Freshwater planted aquariums, with or without a CO2 system
Safe with	Freshwater fish; does not alter pH
Water change needed	No
Made by	Mars Fishcare, USA

In a high-tech tank a liquid carbon source supplements pressurised CO2 injection; it does not replace it.

Do I need a CO2 system as well?

Not for a low-tech tank. CO2 Booster is designed to be used on its own, and for easy plants under moderate light a daily 1 ml per 40 litres is a sensible carbon source that needs no cylinder, regulator or diffuser. If you already inject CO2, keep doing so: the liquid supplements a pressurised system rather than replacing it, and API states the two can be used together. Either way, dose once a day, measure with a syringe and do not exceed the label rate. The 237 ml bottle treats about 8 900 litres, and because it does not alter pH you will not see the pH drop that injected gas causes.

Supplies the carbon most planted tanks run short of

Light and nutrients only go so far if there is no carbon to build with. CO2 Booster dissolves simple carbon compounds into the water column, where they slowly release CO2 that plants use for photosynthesis. Growth that was being held back by a carbon shortage can get moving again without any change to lighting or fertiliser.

Works on its own or alongside pressurised CO2

In a low-tech tank with no gas system, CO2 Booster is the simplest way to give plants a carbon source without cylinders, regulators or diffusers. In a high-tech tank it supplements injection rather than replacing it: a pressurised system remains the stronger carbon source, and API states the liquid can be used together with it.

Does not alter pH and is safe for freshwater fish

Injected CO2 pushes pH down as it dissolves; the liquid form does not change pH at all, so there is no swing to manage when the lights go on or off. API rates CO2 Booster safe for freshwater fish at the label dose. Keep to that dose, because with a carbon supplement more is not better.

One 237 ml bottle treats 8 900 litres

The rate is 1 ml per 40 litres once a day, which keeps a steady trickle of carbon available rather than a weekly spike. A 237 ml bottle covers about 8 900 litres of treated water in total: around seven months on a 40-litre nano tank, or about two months on a 160-litre community tank. A 1 ml syringe makes the small daily doses easy to measure.

Frequently asked questions

Can I use CO2 Booster in a tank without pressurised CO2?

Yes, and that is its main use. API states it may be used alone or together with a CO2 system, so in a low-tech tank it stands in as the carbon source, and in an injected tank it tops up what the gas already provides.

How much CO2 Booster do I add, and how often?

Dose 1 ml for every 40 litres of aquarium water once a day, every day. For a 120-litre tank that is 3 ml daily, and the 237 ml bottle will last that tank around two and a half months.

Will CO2 Booster change my pH?

No. API states it does not alter pH, which is one of the practical differences from injected CO2. Your pH stays wherever your water and substrate put it, so there is no drop checker to watch and no lights-on swing to manage.

Is CO2 Booster safe for fish and shrimp?

API states it is safe for freshwater fish at the label dose of 1 ml per 40 litres daily. The label does not make a separate claim for shrimp or snails, so in an invertebrate tank introduce it at the standard dose, never more, and keep an eye on them.

How quickly will plants respond?

Expect a gradual change rather than an overnight one. The liquid releases carbon slowly, and plants need consistent daily dosing and adequate light to make use of it, so judge results on new growth over a few weeks.

Is API CO2 Booster available in South Africa?

Yes. Jungle Aquatics in Fourways, Johannesburg stocks the 237 ml bottle and delivers across South Africa; current pricing and stock are listed on jungleaquatics.com.

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