LEDs penetrate water extremely well. A great example of LEDs is the taotronic LEDs. These are LED
panels that provide 3 watts per LED
diode, which provides enough power to successfully keep anemone, clam, and SPS
corals. 2-3 watts per diode is enough to keep LPS
With this being said, reflect back to you wanting to keep soft corals. I have read that the Marineland reef compatible LED
unit can support low light soft corals...BUT I don't know how long these units will get and it might be a stretch over a 50 gallon. I personally would either go with a T5HO unit over a 50, like you have for your freshwater tanks, or utilize how cheap the Taotronic units are and use the units that dim to your advantage. This will let you adjust the lighting to exactly your needs and get more light intensive corals down the road if you want to try it, and we always end up doing so.