The thread about leaving the lights off is a decent one. I've been combating a small amount of algae by turning my lights off for 2 days once every 2 weeks. However I will point out that your source of cyano, probably in a similar way to my algae, is caused by an outside controllable force. Just turning the lights off once in a while won't do much of anything. Just before I turn them out I do a 50% water change in my 75g tank, then 2 days after the lights come on I do another 50% water change. I also clean the fuge and bottom of my sump each time. Basically I'm trying to scrub my tank clean while I'm stunting the algaes growth, that way when the lights come on there will be less nutrients for it to consume.

Also if you are having that big of a problem with cyano I'd have to think that you do not have enough flow in your tank. When I started my tank I had a nice sized canister filter, 900GPH return, and a 600gph power head in my tank for flow. I got some nice sized patches of cyano that would appear and then disappear as they used up the nutrients available. What I did find was that once I got my tank up to about 3,800gph that cyano had no place to take hold and grow. It grows best in dead spots.