API pH Proper 6.5 Powder Jar 240gm
Pack size
240 g
Water type
Freshwater
Dose rate
2 tsp per 38 L
Shrimp and invert safe
Yes
Plant safe
No, not for planted tanks
API pH Proper 6.5 Powder Jar 240gm
Buffers to 6.5 and holds it, rather than nudging pH once and leaving it to drift. API Proper pH 6.5 is a powdered buffer for freshwater aquariums that sets pH to 6.5 and resists the tank's natural drift back – suited to soft-water communities such as tetras, rasboras, discus and other Amazonian species. It doses at 2 teaspoons (or one supplied scoop) per 10 US gallons (38 L), sold here in a 240 g jar.
Key features
- Holds pH at 6.5, not just a one-off correction – a phosphate buffer resists drift the way a one-shot pH adjuster can't.
- Also conditions the water – neutralises chlorine and chloramine and detoxifies heavy metals in the same dose.
- Works out to roughly 5.7c per litre of aquarium water treated, at the label dose (see below).
- Simple dosing – 2 teaspoons, or one scoop, per 10 US gallons (38 L).
- 240 g jar – a distributor-stated yield of around 200 US gallons (757 L) at the label dose.
Cost per litre
At API's label dose of 2 teaspoons per 10 US gallons (38 L), a 240 g jar treats an estimated 757 L (about 200 US gallons), based on a specialist distributor's stated pack yield rather than a figure API itself publishes. That works out to roughly 5.7c per litre of treated water.
Specifications
| Type | Powdered pH buffer and water conditioner |
|---|---|
| Target pH | 6.5 |
| Pack size | 240 g jar |
| Dose rate | 2 teaspoons (1 scoop) per 10 US gallons (38 L) |
| Estimated yield | ~757 L (~200 US gal) per jar at label dose |
| Water type | Freshwater only |
| Plant safety | Not recommended for planted tanks |
| Invertebrate safety | Safe, per API |
| Freight | Standard |
How much do I use?
| Aquarium volume | Dose |
|---|---|
| 10 US gal (38 L) | 2 teaspoons (1 scoop) |
| 20 US gal (76 L) | 4 teaspoons (2 scoops) |
| 55 US gal (208 L) | 11 teaspoons (5.5 scoops) |
Dissolve the dose in a small amount of tank water first, then distribute it across the aquarium near the filter outlet. Retest and repeat only if pH has drifted more than 0.2 from 6.5 – this is a buffer, not a one-shot adjuster, so it shouldn't need frequent redosing once the tank has settled.
Ingredients
API's Safety Data Sheet for this specific 6.5 formulation could not be retrieved during this run, so exact percentages are not stated here to avoid guessing. The ingredient classes are consistent with the rest of the API Proper pH range – confirmed on the 7.0 formulation's own SDS – and API's own product description: a phosphate buffer as the main pH-holding agent, a chlorine and chloramine neutraliser, and a heavy-metal detoxifier, plus electrolytes to reduce handling stress. Checked 7 August 2026; flagged below for a supplier SDS follow-up specific to this pack.
Suitable for, and not suitable for
Suitable for:
- Soft-water freshwater communities – tetras, rasboras, discus, Amazonian species
- New tank setup, established tank pH correction, and water changes
- Invertebrate-safe freshwater systems
Not suitable for:
- Planted aquariums – the phosphate buffer binds trace elements live plants need
- Marine or reef aquariums
- Very hard tap water without expecting some temporary cloudiness (harmless, clears within 24–48 hours)
Safety
- Keep out of reach of children
- Shake or stir thoroughly before dosing so the powder disperses evenly
- Avoid direct skin and eye contact with the concentrated powder
- Store the jar sealed and dry
Goes well with
- API Freshwater Master Multi Test Kit 5 in 1 – confirm pH is holding at 6.5 and check KH, which drives how often you'll need to redose.
- API pH Down – for an established tank that needs a larger initial pH correction before this buffer takes over holding it.
- API Quick Start – live nitrifying bacteria for new tank setups, which this product is also commonly dosed during.
Warranty and delivery
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.
Common questions
Is this a one-off pH adjuster or an ongoing buffer?
It's a buffer – it's designed to hold pH at 6.5 against the tank's natural drift, rather than moving pH once like API pH Down. You should need to redose only when a test shows pH has drifted more than 0.2 from the target.
Can I use this in a planted tank?
API advises against it. The phosphate buffer binds trace elements that live plants need, so a planted display is better served by an unbuffered pH product or by managing pH through other means.
Why did my water go cloudy after dosing?
Temporary cloudiness in hard water is a known, harmless reaction as the buffer interacts with dissolved minerals. It typically clears within 24 to 48 hours and does not affect fish.
Is it safe for shrimp and snails?
API states the product is safe for invertebrates. As with any new product, dose at the stated rate and monitor rather than double-dosing on a heavily stocked invertebrate tank.
How much does one jar cost per litre of water treated?
Based on a distributor-stated yield of around 757 L per 240 g jar at the label dose, and this store's price, that's roughly 5.7c per litre – cheaper than repeatedly dosing a liquid one-shot adjuster to the same effect.
