Through the summer we were battling a cyano outbreak and here is what we found:
No single thing totally cured our problem, it was a combination of small changes over time that really helped. First thing we did was change our bulbs to ATI, our T5's were at 11 months old and changing them out helped a lot.
Secondly we added a canister filter, dumped all the media that came with it and added coarse pad -> carbon pad -> phosphate pad -> nitrate pad and finally a water polishing pad. I think all the pads came to around $25 and we get 3 filters per pad. We change pads every other week, it's something you have to do or you can create a nitrate factory in the filter.
Thirdly over the course of a couple of weeks we changed our lighting cycle, we cut our white lighting period back to a little over 6 hours a day. Actinic's come on at 8.30am and run for around 13 hours, whites kick on around midday and run until around 6.30pm.
10% water changes every week for a month, we actually got our water from our local LFS and combined the canister filter changes along with our water changes. Now we're back on a bi-weekly cycle of changes unless we see something happening we don't like.
When we started all of our testing was coming back with numbers that were good but not perfect. Now we have very good numbers and the tank is doing better than it has at any point before. We have very good coral extension, very good growth even on some of the slower growing corals and the cyano is gone.
It wasn't an overnight fix and it wasn't very quick really but it worked, didn't cost thousands (probably around $125 not including the bulbs) and more importantly for us we now have a regular system for doing maintenance that we stick to.
Hope that helps give you a few pointers to small changes that do help.