API pH Down

API pH Down uses phosphoric acid to reduce aquarium pH rapidly, making tap water suitable for soft-water species such as discus, tetras, and apistogrammas that require conditions below pH 7.0. The liquid format allows small incremental additions for controlled adjustment.

Because pH Down relies on acid addition rather than buffering, its effect can be temporary in hard or high-KH water. For a lasting reduction in tanks with moderate-to-high carbonate hardness, it should be combined with a KH-reducing approach such as RO water dilution or peat filtration.

API pH Down is intended for freshwater aquariums only and should always be used with a reliable pH test kit to avoid overshooting the target.