Well, if you want the Grassto grow fast, give plenty of 6500k (3 or 4 watts/g), if you want Inverts to grow at their best ability, give them more blue, like 14000k/actinic blue). Plants in the Northern hemisphere grow best at a light around 6500k to 7500k, Souther hemisphere plants like 5500k to 6500k light spectrum. Corals are not my expertise but I have had many planted FW tanks.

Hope this helps some way.