I just got the 20w 6000-6500k LED
floodlight in for my freshwater tank and the difference between it and the 10w is amazing. It's far far brighter than the 10w, almost to bright. I'll have to see if it'll cause any unwanted algae growth. The difference is huge.
Summary: I had originally ordered 2 10w LED
floodlights and thought they were to dim for my 20H planted tank. I then replaced one 10w for a 20w and now I may just remove the other 10W.
Edit: I took off the other 10w. One 20w LED
floodlight seems plenty bright for a "high light" planted tank. Still, only time will tell for sure.