You need to start dosing some GH booster or Seachem's Equillibrium to get back the calcium and magnesium you removed. And, all plants need nutrients, so you need to be dosing fertilizers, especially with that much light. I suggest getting a half dozen or so cheap little fish in there too, to make sure the tank cycles. And, for that much light you need a source of carbon for the plants, so adding Excel would be a good idea if you don't want to use CO2.
There are going to be algae spores in your water and substrate no matter what you do, so the goal is to keep the plants growing well and in good health, and avoid any spikes of ammonia, plus avoid any shortages or wild changes in CO2 in the water - the latter two would tell the algae spores to start blooming.
Read Rex Griggs guide for more information.