API pH UP for Freshwater Aquariums API has been an industry leader in fish care, nutrition, treatments, testing and pond products for over 50 years, giving them a keen insight into your aquarium and its needs - making them the clear choice for fish enthusiasts around the world. API pH UP pH adjuster raises pH levels in your aquarium to make water more alkaline when levels fall too low. pH is the measure of acidic or alkaline conditions in water, where a value of 7.0 corresponds to a neutral pH, pH values above 7.0 are considered alkaline, and pH values below 7.0 are considered acidic. Different fish need different pH levels to be healthy, so it is important to test your water regularly to ensure pH levels fall where they should. pH UP pH adjuster is fast-acting, colourless, easy to use, and will not cloud aquarium water. Because it is phosphate-free and nitrate-free, pH UP pH adjuster will not encourage algae growth. Water treatment to raise the pH (make the water more alkaline) Use when the pH falls too low Suitable for freshwater aquariums Fast-acting, colourless, and will not cloud the water After something different? View all Fish Water Care Supplies. New to fish care? View our guide to Setting Up a Fishtank.