This is the common wisdom, but it may not be supported. From an upcoming article by me and Chris Jury:
"Two other recent studies have really begun to blow the lid off of what we thought we knew about the effects of elevated phosphate on corals. Godinot et al. (2011) examined the effects of phosphate concentration (0.00, 0.05, and 0.25 ppm) on growth and various physiological responses of the coral Stylophora pistillata. Similarly, Dunn et al. (2012) examined the effects of phosphate enrichment (0.09, 0.2, and 0.5 ppm) on the coral Acropora muricata. Both of these studies were performed in aquaria where at least some of the negative indirect effects of nutrient enrichment which can occur on a real coral reef, such as algal overgrowth, could be minimized. Surprisingly, in both studies the corals grew fastest at the highest phosphate concentrations tested (0.25 and 0.5 ppm, respectively). In fact, the rate of coral growth for both species increased linearly with the phosphate concentration. At least for A. muricata, skeletal density was also lowest for the rapidly-growing corals in the high phosphate concentration, though reduced skeletal density during periods of rapid growth is not necessarily unusual for corals. Hence, these corals were growing fastest and appeared to be "œhappier" at phosphate concentrations on the order of 5-10x greater than the commonly recommended upper limit for reef tanks, or about 10-50x the phosphate concentration typically observed on most coral reefs"