Most people would recommend fixtures with 3-watt LEDs on them. I would say it depends on the size of your tank. If you follow one of the topics here, you will find that they set them only at a quarter or not even half of the full capacity of their lighting fixtures. That means only about 1 watt or less of each LED
is being utilized. The height of your water in your tank dictates the intensity of light or PAR you need. In my case, I have a shallow reef tank with only about 15 inch water. I use a reef capable 1-watt LED
and I have to raise it 8 inches above the water surface since above water the loses is less than in salt water. As long as corals are directly underneath, it will work. I have SPS
and they grow.