There are 2 types of fixture designs available.
Point fixtures are designed to create a dramatic effect by enhancing shadows and giving shimmer. Panel fixtures are designed to provide a blanket of coverage. They are at an opposing end of the light physics spectrum. There are fixtures that use small panels with lenses to walk the line between the two, but in the end there is "no replacement for displacement" when it comes to shadow reduction.
Shimmer and shadow are "vanity" effects. They give depth and movement to the tank, an important aspect as we pay $$$ for these things to look good. Blanket coverage provides a healthier growing environment for corals as it overcomes colony shadowing.
If you just want shimmer/ shadow, you can have a beautiful tank with a few kessils and proper coral placement. Several fixtures are required to help overcome colonies shadowing themselves. (ex. rather than 1 a360x, use 2 a160 or 4 a80... rather than 1 a500x, use 2 a360x)
The other aspect of shimmer/ shadow is that it takes a very small amount of par to create a dramatic visual effect. Our eyes are most sensitive to the 500-600 nm "white" zone.
Rather than replace the diffuser of a panel fixture with a clear piece, I would recommend keeping the stock diffuser and adding a dedicated shimmer light. The nutrition for the corals will be provided by the blanket of light while the shimmer will be provided by the shimmer light.
If you have 2 SKY it is simple, just throw a kessil in the middle. Even an a80 will be sufficient to give the look. If you have 1 SKY, I would look at
Amazon for a cheap, small white led and mount it in the center of the panel. You can try it with your cell phone, just turn on the flashlight and hold it in the middle of the panel.
www.reef2reef.com
