• Holds pH at a neutral 7.0 — a phosphate buffer resists drift rather than making a one-off correction.
• Also conditions the water — neutralises chlorine and chloramine and detoxifies heavy metals in the same dose.
• Suits mixed community tanks — 7.0 is the safe middle ground when housing several species with different pH preferences.
• Works out to roughly 5.4c per litre of aquarium water treated, at the label dose.
• 250 g jar — a distributor-stated yield of around 787 L (208 US gallons) at the label dose.

At API's label dose of 2 teaspoons per 10 US gallons (38 L), a 250 g jar treats an estimated 787 L (about 208 US gallons), based on a specialist distributor's stated pack yield rather than a figure API itself publishes. At $42.95 per jar, that works out to roughly 5.4c per litre of treated water — marginally cheaper per litre than the 6.5 formulation's 240 g jar, because this pack is slightly larger for the same price.

Dissolve the dose in a small amount of tank water, then distribute it near the filter outlet. Retest and repeat only when pH has drifted more than 0.2 from 7.0.

Transcribed from API's Safety Data Sheet for this product, checked 7 August 2026:

API's SDS notes that the exact chemical identity and precise concentration of the phosphate buffer are withheld as a trade secret; the ranges above are as published.

Suitable for:

• General freshwater community tanks housing several species with different pH preferences
• New tank setup, established tank correction, and water changes

Not suitable for:

• Planted aquariums — the phosphate buffer binds trace elements live plants need
• Marine or reef aquariums
• Soft-water specialist tanks needing 6.5 or lower, or alkaline specialist tanks needing 7.5 or higher — API sells dedicated buffers for those targets

API's Safety Data Sheet for this product carries hazard statements for the concentrated powder, before it's diluted into tank water: causes skin irritation, causes serious eye irritation, may cause respiratory irritation, and is classified toxic to aquatic life in its concentrated form. Handle the dry powder accordingly:

• Keep out of reach of children
• Avoid raising dust; measure with the supplied scoop rather than pouring loosely
• Avoid skin and eye contact with the powder; wash out eyes with fresh running water immediately if it happens
• Dissolve fully in tank water before use — the aquatic-life hazard applies to the concentrate, not to the tank once correctly dosed and diluted

• API Freshwater Master Multi Test Kit 5 in 1 — confirm pH is holding at 7.0 and check KH.
• API pH Down or API pH Up — for a larger initial correction before this buffer takes over holding the level.
• API Quick Start — live nitrifying bacteria for new tank setups.

This is a consumable, so no manufacturer warranty period applies. That does not affect your rights under the Australian Consumer Law: if the product is faulty, unsafe or not as described, you are entitled to a remedy.

Ships as standard freight.

What's actually in this product?

API's Safety Data Sheet lists a proprietary phosphate buffer at over 60%, sodium thiosulfate (a dechlorinator) at 1–5%, and EDTA tetrasodium salt (a heavy-metal detoxifier) at 1–5%. The exact phosphate salt is withheld as a trade secret.

Is this the same as API pH Up or pH Down?

No. Those are one-shot liquid adjusters that move pH and then leave it to drift. This is a powdered buffer that sets pH to 7.0 and resists drift, so it needs redosing far less often.

Can I use this in a planted tank?

API advises against it, since the phosphate buffer binds trace elements live plants need.

Why did my water go cloudy after dosing?

Temporary cloudiness in hard water is a known, harmless reaction. It typically clears within 24 to 48 hours.

How much does a jar cost per litre of water treated?

Based on a distributor-stated yield of around 787 L per 250 g jar at the label dose, and this store's price, that's roughly 5.4c per litre.