The water is the same in the Display Tank, the Refugium and the Algae Turf Scrubber. The main reason the Refugium and the Turf Scrubber "outcompete" the algae in the DT is that the lights are more powerful and more aligned to the algae's needs. It will grow faster there than in the DT. Diminishing the whites in the DT might help this happen even faster but isn't necessary. Algae eating fish and cleanup crew also keep the algae down in the DT and increase the difference between the environments so algae grows where you want it and not where you don't.