To Specify You Do not Need the Shaders Mod. You only Need Optifine
This is an indev texture pack that changes the fog, sky and cloud color like indev use to do by theme. This does not , I repeat Does not need the shaders mod and is called shaders only because, it only changes the cloud, fog , and sky color which are vanilla shaders.
There are four shaders like in Indev there are four themes. There is Hell, Normal, Paradise, And Woods. They each have different rgb values then current vanilla. For example although the normal indev theme might look almost like the current minecraft texturepack only the cloud color is the same. In the rgb values the fog is white, the sky is lighter blue and the clouds are in the same formatting you would see in indev except if you 3d fancy render your clouds.