When you move all the contents of a tank from one to another, it upsets the balance of the system. The microorganisms in the system that had adapted to their situation now have different placement with respect to flow and lighting, so you will likely end up with a mini-cycle, albeit one that you cannot "see" on your test kits. This can result in a short-term algae outbreak and can be exacerbated by a change in lighting as well (which I'm guessing is the case as well). Moving rocks and substrate (and changing the flow patterns) can also cause trapped N and P to leech out, so the fact that your N is low but your P is up leads me to think that this is the case, and the algae on the rocks is sucking up the P that leeches out first, but there's still enough to get into the water column.
Make sure your screen has plenty of flow and light, even extra light if necessary for a short time, as long as you don't start getting yellow rubbery growth, you can throw as much light as you want on it. You can also up the light and decrease the "on" time per the new lighting guidelines if you get the yellow growth. You want green growth, which does the best filtering. Also don't black out the light in the DT, this will just cause the algae to die and release the nutrients into the water and could overwhelm the scrubber if it isn't strong enough, as well as stressing any corals you have. The corals will help pull nutrients (food) out of the water so you don't want to slow that process by cutting out the light.
HTH
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