"The concentrated formula of Gold-N-Clear® uses color-changing technology to show that it's working! Watch the product change from gold to blue as it removes micro-particles, leaving the water sparkling clear. Regular use of Gold-N-Clear® will help your filter do its job more efficiently. Useful Tips: Clears cloudy water fast Unique color changing action indicates that it's working Highly concentrated formula Compatible with all sanitizers including bromine, chlorine, salt water, ozone, minerals and biguanide"