You never are going to have large numbers of zooplankton in your reef unless you remove your fish and filtration system. Dumping phyto in our tank was popular a long time ago for the reasons you say but we found this out long time ago not to be true. The only thing it helps is filter feeders like sponges, some bi-valves, tunicates, clams, feather dusters etc. not corals. It would grow copepod populations but the ones we want that live in the water columns dont survive in our tanks unless again we remove our fish, filteration system and corals.