Prolight Highpowered LED questions

One of the options i have for my fish tank is to have custom LED lighting that i will make. I want to have a daytime/nighttime setting and i want a RGB Prolight module to do it with. I was looking at what phil has and theya re all 1 watt, i am sure that would be enough but there are no RGB versions. I suppose i can search elsewhere as i have been so far anyways. I need to know, i have been reading the manufacturer pdf and it states that the star modules should be used with a heatsink, is it really necessary? and what is the difference between the star and emitter version depsite the fact that one is a star and the other is just the emitter, is there any mechanical difference to how they perform? I want to be able to stack a bunch of them togetherso that i get good coverage in the tank.