Green Algae is forming on a few wicks. What can I do to prevent it? - The Bug-Man, Tallahassee, Florida
Algae need light and moisture to grow. Since you cannot deprive them of moisture, you must eliminate sources of light such as light transmitting tubing, tanks and containers. One way to do this is to cover the hydro area with reflective material which bounces the light back up to the plants rather than letting it penetrate to the root area. Some people make collars using Mylar or aluminum foil to prevent light getting to the planting medium.
Adding a 1/2% hydrogen peroxide solution to the planting mix every three days will keep all the algae in check. Using a UV-C water sterilizer that is made for hot tubs will also keep the water clear.
I am Using perlite as a growing medium for my hydroponic garden. The problem is that it turns green. - HempTech, Fallsburg, New York
Perlite’s crevices hold nutrient-rich water that makes an ideal home for algae. To prevent algal growth, the top of the medium should be kept dry. Ebb-and-flow system should be set at a shallower flood level and drip emitters should be placed under the surface. Another way to prevent growth is to place black shadecloth or reflective Mylar over the medium’s surface.
A 1/2% hydrogen peroxide solution will also keep the algae in check. It should be added every 3 days.
-Ed Rosenthal The Best of Ask Ed: Your Marijuana Questions Answered