Green Algae Problems

by Jerel Wenger
(West Park, NY)

We have a hydroponic system with a really bad algae problem. Algae is clinging to the roots. Even after cleaning and changing the water, it just grows back the next day. Please help!

Answer: Jerel- algae grows whenever three things are present....water, nutrients, and light. In order to stop the algae, you need to take away one of these three ingredients. Since your hydroponic system is designed to carry water and nutrients all the time, the only option is to eliminate light from coming in contact with the nutrient solution wherever possible.

Start with the nutrient reservoir....make sure you have a nice dark one. Make sure to use a lid on your nutrient reservoir (cut holes just big enough for hoses and cords if you have to). Next, make sure the hydroponic system itself is not letting in a bunch of light. If it is, wrap in in black plastic or aluminum foil. Make sure your plants fit tightly into your system and do not allow light to get in.

If you are using a drip system, cover the surface of your growing medium with black plastic and run your drip emitter underneath the plastic. Otherwise, cut a small hole in the surface of the plastic to minimize the area exposed to light. Be equally protective of the nutrient solution on its way back to the reservoir.

It will take a little while for the algae that is already established to die back. While it is dying back, the dead algae may attract fungus gnats. You could use a weak hydrogen peroxide solution in the nutrient reservoir, but you want to make extra sure you follow the directions for mixing the solution for using with live plants! The peroxide will help clear out the algae and also prevent fungus gnats and other diseases.

Otherwise just let the algae die back naturally, and do an extra water change if the solution gets too funky. Once it is established, sometimes it does not want to leave. Hopefully it will not cause too many other problems! Good luck!