I'm sure other hobbyists have covered it nicely but just after reading your initial post, you do have a phosphate issue. The 0ppm reading is after the Cyano has either already stripped it from the water column leaving you 0ppm reading or is directly uptaking it from your rocks which are most likely leaching phosphates.
You remedy this by removing phosphate in whatever method you choose, reactors, refugiums, or water changes. Slowly, over time, your phosphate level will be manageable as you'll remove more than as via feeding and leaching and you'll win the battle.
You remedy this by removing phosphate in whatever method you choose, reactors, refugiums, or water changes. Slowly, over time, your phosphate level will be manageable as you'll remove more than as via feeding and leaching and you'll win the battle.