I agree with justletmein you should get an R/O unit. Champion lighting has specials on Kent R/O units I think there are bare-bones ones for $80 that would be good enough but I would at least go with the three stage.
http://www.championlighting.com/e/en.../rofilter.html
You can also get some at Home depot that are really good and I think they are only about $150.
Life is so much simpler with an R/O unit, and your tank should quickly outgrow those cyano probs. Make sure you have enough light though?