I finally have my first system almost ready to start. It's based on a 75 gallon aquarium that connects to two half barrels. I have designed the system with mobility and transparency in mind because it will eventually be moved to an elementary school. In the meantime, I am trying it out in my backyard. Can anyone recommend a good way to cover the aquarium so that it doesn't get too much algae growth from direct sunlight? Right now, its completely exposed and I don't have a greenhouse or any other place to put it. Thanks!