The frequent watering needed to germinate seed can encourage the establishment of algae. Good air movement is also important and fans may be needed in certain conditions to enhance air movement across the soil surface. The pH of the soil should also be checked. Apply your algae control to established algae that are actively growing, but before crust formation. The application of iron or other pH-altering materials can assist in creating an environment unfavorable to algae growth.
Fungicides can also be useful in the control of algae.