Cyano Outbreak Help!

[saltymarine]

I have Cyano all over my sand how can I get rid of it? I have checked my water and everything is good how can I get rid of this stuff?
Nitrate: 0
Nitrite: 0
Ammonia: 0
pH: 8.2
SG: 1.025
I do weekly 25% water changes on my 29G using RO water from a water machine until the outbreak now I use Wal-Mart bottled water. I don't add anything to the tank and so far I tried a water change, adding carbon, and so far nothing.

 

[saltymarine]

Also, I read that sometimes it is the bulbs but I don't think this is the problem because I just bought them and put them in 2 weeks ago. I read that leaving the lights out for 5 days may solve the problem but will it kill my corals? I have just a few button polyps, some star polyps that do not come out any more and some mushrooms.

 

[uneverno]

Check post 3 here:https://forums.saltwaterfish.com/t/354428/cyano-question-theory
I cut back white light to 6hrs/day, 25% water changes w/RODI water every other day.
Took 3 weeks, but worked like a charm.