Kind of. If the PO4 is lets say 0 in the water column but you have algae growing, there has to be PO4 'in the system'. But its out competing the coral. Im not sure you can base cyano on the amount of PO4 as compared to other things - though same say you can. The bottom line is your PO4 in your water (which is where the coral get PO4 from) is lower than recommended.
Yeah it’s just when to add some media to combat po4 being to high, knowing when to is hard as like I said I think testing is pointless.
I often wonder if the carbon dosing also keeps po4 low.
