Thought I would share this idea I have used on all my tanks for a while now and works extremely well.
What first made me think of this idea was that my fish tanks are set in such a way (when washing up or on the computer )I can not see in the tank,so I used plain black reverse blue tank backing and cut it at aprox 45 degrees taping the back edge with duck tape to act like a hinge and fix a piece of duck tape to secure the front bottom end(as in pic.)This allows me to see my fish and and tank end view but also allows the fish their privacy,but if I need to check they are ok (In good health or still in the land of the living

I think its a brill idea and has worked for me,also I have found that over time do not get a build up of alga and looks quite neat.

Here is a pic 6'x2'x2' end
Jerry