This hobby is definitely one that requires patience.
One month from removing a suspected problem is not very long. It can take many months for a problem to go away, once you've identified it.
It's been pointed out to here you a possible source of your problem, but I'm not sure why you didn't respond to it.
You don't need to buy a phosphate reactor, just an absorbing media of some kind. I've never used any, so I can't recommend one.
Live rock is porous, so it makes sense that it can absorb stuff. The parts of the live rock that were previously buried under the sand didn't have water flowing past it, so phosphate could have concentrated in the live rock in those areas. The same could be said for areas of the live rock that had detritus accumulating in it's crevices, where there was little or no water circulating past it. Phosphate could have built up in those areas too.
Bacteria also lives within live rock, just like in a DSB, only the anaerobic zone is much closer to the surface than in a DSB. As the bacteria reproduces, it will actually push out particulate matter which needs to be blown away with water current.
That's also the principal behind the action of "bacterial turgor", someone correct me if I'm wrong.
In a DSB, on the bottom of live rock that is buried in sand and on live rock that has detritus accumulating on it, there is no water washing away the particulate matter, so the concentration of stuff like phosphate will only increase. The concentration will build up to a point where it can't absorb any more, so it will start leaching it out into the water faster than it can be taken away.
That's when the algae starts.
The bacterial turgor
will clean the live rock, but it takes time.
In a perfect set-up, you would have a piece of live rock suspended from a string in the middle of a tank with a few powerheads pointed at it.:lol:
(which isn't too far from some of the "starboard bottom" setups I've seen!:wink
Sure, you can sell your live rock and buy new stuff, but the same thing will happen if you don't have sufficient water circulation and a means of nutrient/phosphate export.
Mitch