GreenClean Concentrate Blue Colorant for Koi Ponds & Water Features, 16 Oz.GreenClean Blue Colorant defends against the sun to protect water quality and clarity. When it is added to water, the first benefit is the aesthetically satisfying blue tone that develops. This blue tone serves another purpose aside from being attractive, it works to block the suns UV rays that promote excess aquatic algae growth and organic buildup. This added feature of protection is especially important for water features that receive part or full