Most efflos/solis have a good bit of brown in them to being with. In my experience the less nutrients you have in the tank the lighter (more brown) solis/efflos get. However, there is a lot that comes into play with any coral as far as coloring.
When I slack off on keeping up with the tank and let the BB tank go a month or two (sometimes more) without cleaning the soli usually pulls in a lot more green. However, at the same time I just had the CA reactor down for about 3 months and didn't work on the tank at all in that time and the soli got really light.