Akwarius
2500 Club Member
Ok, so here's my dappled light theory. As most of you know, with Planet Zoa, I have several shallow tanks filled with every type of zoa imaginable, all lit by radion leds. Tinkering with the intensity and spectrum, specifically cranking the cree whites way down, goes along way to achieving that zoa nirvana that everyone wants but few have attained. 
But, in my system, there was still something missing.
Now, I watch the "Blue Planet" series at least once all the way through per month. For those of you with small kids, you'll understand how valuable something like this can be for calming your child down. Anyway, I noticed the way that the light bends through the random, rippling ocean surface and diffracts through the water (see pic below). Unlike some reef aquariums, surfaces under the sea arent blasted with constant, intense light. Instead they are lit by a constantly shifting kaleidoscope of "dappled" light. Im sure if you took a par reading in full sun it would be much greater than that of our leds, but the light is never in one place for very long. I began to wonder if this mattered.
The intense light needed for sps might mitigate this problem, however, for lower light corals, or corals found in deeper water may experience greater light "shock" under constant, direct light, especially considering how dappled the light is at that depth. In addition, I've always noticed that my shaded zoas grew at a slightly faster rate. For example, we've all seen zoas stretch toward light, and shrink under too much light. Expanding on this further, perhaps they are biologically "programmed" to grow more quickly when light is less abundant, but still abundant enough to meet base-line photosynthetic needs. Lets create a scenario. On an actual reef, lets say a branchy stag coral was growing rapidly above a zoa colony, thus shading it slightly. The zoas under the stag might be triggered to grow faster in order to "compete" with this diminishing light.
Other evidence for this theory: zoas tend to grow more quickly and robustly at the bottom of deep tanks with an intense, single-light source such as halides. This type of tank would have very impressive dappling while still maintaining par great enough for light hungry zoas.
So I started wondering if this could be mimicked in a shallow tank. Raising my LEDs and lowering the zoas in the water column helped, as did increasing the surface agitation by moving the vortech wave makers. All of these steps increased the amount of light dappling in the tank. The biggest difference was seen, however, after adding my simple dappling screens. Dont worry, this isnt a sales pitch.
I've made a diagram below of a simple dappling screen. Simply take a standard eggcrate light diffuser, and "plug" some of the holes with foam. I prefer to use the flexible, closed-cell foam that usually comes with electronics because its easier to cut into little 3/4" squares. As you can imagine, the amount of shading can be easily adjusted by adding or subtracting the foam plugs.
The result (with pumps off) is a shadow "grid" that is cast over the corals. Nothing special with the pumps off. But when you increase the surface agitation, the light bends and dapples, much like what I initially noticed in the "Blue Planet" DVD. If done just right, you'll have light dancing across your corals, rather than "blasting" them in a "light box". Some of you may be thinking that this is an extraneous waste of electricity. But, shouldnt we strive to more closely mimic the natural reef habitat? A piece of eggcrate, recycled foam, and a little wasted electricity is a very small price to pay if it could improve the health and growth of your zoas.
Light dappling screen:
But, in my system, there was still something missing.Now, I watch the "Blue Planet" series at least once all the way through per month. For those of you with small kids, you'll understand how valuable something like this can be for calming your child down. Anyway, I noticed the way that the light bends through the random, rippling ocean surface and diffracts through the water (see pic below). Unlike some reef aquariums, surfaces under the sea arent blasted with constant, intense light. Instead they are lit by a constantly shifting kaleidoscope of "dappled" light. Im sure if you took a par reading in full sun it would be much greater than that of our leds, but the light is never in one place for very long. I began to wonder if this mattered.
The intense light needed for sps might mitigate this problem, however, for lower light corals, or corals found in deeper water may experience greater light "shock" under constant, direct light, especially considering how dappled the light is at that depth. In addition, I've always noticed that my shaded zoas grew at a slightly faster rate. For example, we've all seen zoas stretch toward light, and shrink under too much light. Expanding on this further, perhaps they are biologically "programmed" to grow more quickly when light is less abundant, but still abundant enough to meet base-line photosynthetic needs. Lets create a scenario. On an actual reef, lets say a branchy stag coral was growing rapidly above a zoa colony, thus shading it slightly. The zoas under the stag might be triggered to grow faster in order to "compete" with this diminishing light.
Other evidence for this theory: zoas tend to grow more quickly and robustly at the bottom of deep tanks with an intense, single-light source such as halides. This type of tank would have very impressive dappling while still maintaining par great enough for light hungry zoas.
So I started wondering if this could be mimicked in a shallow tank. Raising my LEDs and lowering the zoas in the water column helped, as did increasing the surface agitation by moving the vortech wave makers. All of these steps increased the amount of light dappling in the tank. The biggest difference was seen, however, after adding my simple dappling screens. Dont worry, this isnt a sales pitch.
I've made a diagram below of a simple dappling screen. Simply take a standard eggcrate light diffuser, and "plug" some of the holes with foam. I prefer to use the flexible, closed-cell foam that usually comes with electronics because its easier to cut into little 3/4" squares. As you can imagine, the amount of shading can be easily adjusted by adding or subtracting the foam plugs.
The result (with pumps off) is a shadow "grid" that is cast over the corals. Nothing special with the pumps off. But when you increase the surface agitation, the light bends and dapples, much like what I initially noticed in the "Blue Planet" DVD. If done just right, you'll have light dancing across your corals, rather than "blasting" them in a "light box". Some of you may be thinking that this is an extraneous waste of electricity. But, shouldnt we strive to more closely mimic the natural reef habitat? A piece of eggcrate, recycled foam, and a little wasted electricity is a very small price to pay if it could improve the health and growth of your zoas.
Light dappling screen:
