Pond Care

API Pond pH Down

PondPhosphate-free

API Pond pH Down lowers the pH of pond water gradually by neutralising the alkaline substances that push it up — often limestone rockwork, concrete or hard tap water. High pH is not only a fish problem: it limits the ability of aquatic plants to take up the nutrients they need, so lilies and marginals stall. The formula is safe for pond fish and plants and contains no phosphates, so it does not feed algae the way some pH products do. Test with the Wide Range pH Test Kit, dose 5 ml per 189 litres, and retest after 24 hours. The bottle holds 473 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 pond volume and the calculator works out how much API Pond pH Down to use for each rate on the pack.

Pond volume

Measured in

Use length × width × average depth in metres × 1 000 = litres.

Single dose5 ml per 189 litres
Enter a volumeAdd to the water flow, then retest after 24 hours

Lower pH in steps — test with the Pond Wide Range pH Test Kit between doses.

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 pond pH reducer
Pack size	473 ml
Dose	5 ml per 189 litres
Retest	After 24 hours; repeat as necessary
Phosphate	Phosphate-free — will not promote algae
Suitable for	Garden and koi ponds
Safe with	Pond fish and aquatic plants
Test with	API Pond Wide Range pH Test Kit (5.0 – 9.0)
Made by	Mars Fishcare, USA

Why is my pond pH so high, and how far should I lower it?

Usually because something alkaline is in contact with the water: limestone or dolomite rock, new concrete or render, or simply hard tap water topping up through a dry summer. Aim for the 7.0 to 8.5 band koi and goldfish do best in, and get there in steps: dose 5 ml per 189 litres — about 130 ml in a 5 000-litre pond — wait 24 hours, test with the Wide Range kit and repeat if needed. If the reading climbs straight back, the cause is still in the pond; sealing new concrete or removing limestone does more than repeated dosing. The formula is phosphate-free, so it will not feed algae while you work.

Gradual, and safe for stocked ponds

The product neutralises alkaline substances slowly so the pond drifts down in steps rather than dropping. Dose, wait a full day, test, and repeat only if needed — the same discipline that protects fish in an aquarium applies outdoors, where volumes are larger and mistakes are more expensive.

No phosphate, no algae bonus

Some pH-lowering products are phosphate-based, which is the last thing a summer pond needs: phosphate is the nutrient behind green water and blanketweed. Pond pH Down contains none, so correcting pH does not hand the algae a meal.

Plants feed better at the right pH

When pH runs high, several nutrients become chemically unavailable to aquatic plants regardless of how much fertiliser is in the soil. Bringing the pH into range lets lilies and marginals use what is there — worth pairing with Aquatic Plant Food Tablets in the baskets.

Frequently asked questions

Does Pond pH Down contain phosphates?

No. It is phosphate-free, so unlike some pH products it does not add the nutrient that drives green water and blanketweed.

How much should I dose?

5 ml for every 189 litres of pond water, then retest after 24 hours and repeat only if the pH is still too high.

Why does high pH affect my pond plants?

At high pH several nutrients become chemically unavailable, so plants cannot take them up even when they are present in the water or soil.

Is it safe for koi?

Yes, at the label dose and lowered gradually. Sudden pH changes are what harm fish, which is why the product works slowly and calls for a 24-hour wait between doses.

Is API Pond pH Down available in South Africa?

Yes — the 473 ml bottle is available from Jungle Aquatics in Fourways, Johannesburg, with delivery nationwide; 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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