Not to hijack but I'm having the same considerations and experience around phosphate...
If I may... I have a 10 month old 132 gallon tank. Started with dry marko rock. All rocks are covered in coralline algae and have a green tinge to them. Moderate livestock capacity with some euphyllia, CUC, and tangs. I've been dosing phosphates mildly from 2 months on to maintain them around 0.03 to 0.10 ppm. They always trickle down. Nitrates are always around 10-20 ppm (never dose nitrate).
Recently, for whatever reason, phosphates plunged to 0 and a larger phosphate dose using Seachem Phosphorus did nothing using the Hanna checker.
Should I continue dosing, striving for around a 0.05-0.10 ppm phosphate stability range? I'm concerned adding a bunch of one chemical artificially over time will have negative consequences down the road...