Running lower PO4 will help minimize nuisance algae, and .2 is risking algae growth --unless you have a school of tangs to manage it for you.
GFO is fine IN MODERATION, but before you do that, two things:
a) Start measuring nitrates occasionally. You need to have a bit of both for SPS.
b) Get a real PO4 tester (if u haven't already) Hanna ULR Phosphate checker, and check frequently once the GFO is running.
For the millionth time, go slow and test often (every 3-4 days). Rowaphos strips quick, Phosban works. Both should be rinsed well and used in moderation. All is cool with gradual change. You will know it is spent when PO4 begins rising again.
Please believe me when I tell you that the price of stripping PO4 to 0 is heavy. You will be reading 7,600 posts regarding dinoflagellates, battling 3 hours per day, and buying stuff (extra dosers, UV, testing reagents, obscure sources of phosphate and nitrate, etc) that you should be spending on corals and fish.