Cubecaps 

Eliminate algae and the breeding ground for fungus gnats in your hydroponics with the pesticide-free CubeCap! 

CubeCap blocks the light from your growing medium, which algae needs to survive. It's unique shape also promotes airflow around the top of the growing medium allowing moisture to evaporate in the top layers.

The lack of the light and moisture at the top of your growing medium eliminates algae. Without algae, fungus gnats disappear.

Other benefits:

The top 1/3 of your plant's root mass are air specialized so when the top of the block is kept dryer, more oxygen is available to these roots. More oxygen equals stronger growth!

Growlight is reflected back up to the underside of the plant leaves, increasing light level and creating accelerated growth!

CubeCaps help retain water in the lower 2/3 of the growing medium so you water less often, saving nutrient costs!

Simply place the CubeCap on top of your coco fiber or rockwool cube.

More info from the Manufacturer (PDF format - Lots of detail.)