When I switched to Taos I started down @ 25-30% and maybe bumped them up @ 5% every 7-10 days, if something in your tank starts to look a little off just knock them back to the previous setting for a longer period of time, what people underestimate with these lights is their ability to penetrate the water, the tank may look dim at first but trust me there's plenty of light, I switched from a 6 bulb t5ho fixture to the Taos that's why I started at @ 25% if your current lights are weaker you may want to start at an even lower percentage