Check the listing for details. API Proper pH 7.5 Freshwater Stabalizer Powder 7.5 Ounces. Color: Multi-colored, Condition: New, Made in US. Listed at 16.63 USD. pH is the measure of acidity of water, on a scale ranging from 0 to 14. A pH of 0 is the most acidic, while a pH of 14 is the most alkaline. Water with a pH of 7.0 is considered "neutral". Different geographies have different tap water conditions with different pH levels, while fish require a specific pH level to thrive. API PROPER pH 7.5 Freshwater Aquarium pH Stabilizer automatically sets and stabilizes the pH level in freshwater aquariums to 7.5 which is perfect for Goldfish, Guppies, Barbs, Swordtails, Platies and Mollies. API PROPER pH 7.5 Freshwater Aquarium pH Stabilizer also removes toxic compounds from tap water such as chlorine, neutralizes chloramines, detoxifies heavy metals, and adds electrolytes, making tap water safe for fish.