How deep is the tank, you never stated this critical piece of info. In general, LED's offer poor spread of light, good for spot lighting or from a long distance, but then you lose intensity, so it often ends up being a poor trade off energy wise.
If you chose the Cree 3 W, they offer decent spread and you can space them out evenly over the foot print, the spot light type things do not do that and tend to add too much light, the tannins will go away, too much light will be a thorn in your side for a long long time to come.
Better to go less, rather than more, with light intensity. Especially a lot of light on a larger tank. Great way to grow algae though.