Phosphates are gonna happen, theres no way around them. All the food that you put in your tank contains phosphates, and once broken down they are added to your tank water. You could of course starve your tank to bring down phosphates but that is not a good option at all as I have always seen tanks react better to heavy feedings with heavy filtration vs little feeding and light filtration. Water changes will help some, but the majority of your phosphates are being used up by your hair algae before being allowed to accumulate in your water. To really get phospahtes down, you need either A)refugium or B)phosphate remover(GFO, dont get an iron based one). There is no other long term option other then being really lucky and having so many growing SPS that THEY use up your phosphates, but most people dont have that goin for them =P Usually its the algae that is able to gain the upper hand and not the corals.
As far as the reactor is concerned, id put the carbon before the phopshate remover just to try to make the phopshate media last a little longer. Pay close attention to the dosing instructions. The BIGGEST mistake people make with phosphate removers is that they try to use too much of it off the bat, and it works far too well and their phosphates drop too quickly and their corals start to have problems because they arent so used to such phosphate deffecient water.
Peace,
Jesse
