Chris,
How long have you had your tank set up? I noticed that you had slight traces of ammonia and nitrite...that's why I ask...in a perfect world those should be zero. Your pH could perhaps be a little higher, as well (although it may just be a little low because you took the reading at night). Keeping all of these different readings optimal is a rather large (and constant) struggle for all of us...keep up the fight!
There are many reasons cyano could be growing in your tank. One of the biggest, IMO, is too many nutrients in your tank (caused by such things as overfeeding). These nutrients are gobbled up by cyano. I also see that you're doing a water change...that's great...but what type of water are you using? RO water? Tap water? My experience has been that tap water (not all, but most) contains relatively high levels of phosphates and other goodies that cyano just loves. So when you do a water change, you are, in effect, feeding your cyano. If you don't have one already, I highly recommend an RO or RO/DI unit. Yes, they are expensive, but a wise investment, IMO.
Other things that help keep cyano in check include brisk water movement, "fresh" lighting (I like to change my bulbs once a year), a protein skimmer, and a light-to-medium bioload. Regular water changes are all good, as well.
Good luck, and keep us posted!
Chris
