Maximum Yield USA 2014 February | Page 90

Algae: Friend or foe? While we often think of algae as being a bright green growth in a nutrient solution or on substrate surfaces, the huge number of algal species means their appearance can be quite diverse. Algae can range in color from lime green, to a bubbly black, to red, to brown. These organisms might appear as long stringy filaments flowing in the current or as dense fur on the reservoir and growing channel surfaces. On growing media, algae might appear as a green stain on the surface of a substrate, or as thick, gelatinous slime un