Filippo, take a look at the top few pictures at the beginning of this thread. Simple way to add and remove dense cover as needed, and I use it for FHM cover in my hatchery pond. Drag the brick to the shoreline and flip the limbs over. When you want them out, just pull the brick up the bank, or wade in and flip the limbs back over. Quick, cheap, and easy.
http://forums.pondboss.com/ubbthreads.ph...true#Post515342 Lilies are great cover, but be diligent in your selection if you go that way. With your temperate climate there not may be an actual "season" for them since the minimum temps may stay high enough to have a longer annual growing season. If so, they could spread quicker than you may want. Also, the actual diameter of all the lily stalks may only be 7-8 centimeters for the area you're talking about. Lilies provide shade, but there may better choices for actual fish cover.
Plastic tubs work well for planting lilies.
