We recently started a hydroponic garden and currently are starting lettuce, arugula and spinach from seed. The seedlings are getting along pretty well, in spite of a mid-July start. Over the past week or 10 days there is also a considerable amount of algae growing in the water. Will this hamper the growth of the desired crop? Should we attempt to control the algae growth, and if so, how?
Algae growth is encouraged by light, so make sure your hydroponic reservoir container excludes light. Prevention is safer than treatment with algicide, which is not only phytotoxic, but not something you would want on edible crops.
Here are links which may be of interest:
Hydroponics as a Hobby, from University of Illinois at Urbana-Champaign Extension
Home Hydroponics from Virginia Cooperative Extension.
The information excerpted below comes from a now-defunct page from a home hydroponics website called Maximum Yield:
Other studies have found ‘organic’ algae control methods such as adding certain ‘grapefruit seed extracts’ to the nutrient will kill algae without harming the plants – this is a method used in drinking water, fish ponds, lakes etc. and appears to work well. There could be the potential, in larger hydroponic tanks to use ‘Barley straw rafts’ as a means of algae control as has been proven to work in ponds, lakes and other water ways. However the best method of algae control will still always be prevention of the problem, so excluding light should be the main emphasis in systems with algae problems.