[Gina]

Welcome to RS!
If you use the Chemi-Clean, make sure you follow the directions to the letter.
Turn your skimmer off and make sure you are providing plenty of O2 while you are treating.
Treat the tank for 2 days then follow up with a 20% water change.

When you turn the skimmer on it will be working overtime for about a day.
If you have a sump, that would work out great otherwise you will be cleaning your skimmer cup every couple of minutes.

You could also set up a Phosphate Reactor like mentioned above.
Test your tank water and the water you use to make fresh salt water for Phosphates.
Try to siphon off as much of the cyano as possible and increase your water flow. Check to see if you have any dead spots in your tank.

Hope some of this info helps you get on the right track.
Again, Welcome!