need some input on natural lighting for large tank

[8mycash]

We have bought a new home with a low ceiling, I am able to install light tubes. This will make the pain of moving a 500 gallon tank seem like it is worth it. So I have bought 2 of these 22 inch solar tubes. each one will produce 1,000 watts of light. (according to them). More importantly natural sunlight. The canopy will be rebuilt to reach the ceiling to hide the tubes. I have (4) 400 watts halides along with (2) 250 halides. Question is, would you put both tubes on one side or one on each end with the halides around them.

Here is a picture of the tube.

Here is a picture of my tank.

 

[sfsuphysics]

Well natural light has a power output of approximately 1000 watts per square meter. At 22 inches in diamater each will give about 1/4 sqare meter, so 2 of them is about 500 watts worth of light power.

Now that's all power, they might be talking about the light vs power of light bulbs which don't convert 100% the energy. Although I'd question if each would replace a 1000 watt MH bulb. I'd be interested to see how they work for you though.

Btw I would distrubute them equally, unless you have a particular theme in mind, you might find that they're brighter than you expect and if you put one on either side you might be able to cut back on a bit of lighting.

 

[Chihuahua6]

I have 3 14" Suntunnels installed. The tank is not up yet though. There is a thread about Solatubes in the advanced topics forum. It has been going on for a few years now. Some people use only the tubes and they report good results. Of course they have coverage over the whole tank. Most people add supplemental lighting to the tubes. You should definitely read the whole thread. The only way to determine the true output of the skylights is to use a light meter. Also most of the uv light is filtered through the dome so how much benefit the corals actually get is somewhat of a mystery. When I was designing my lighting plan (after the tubes were already installed) Anthony Calfo suggested that I choose my lamps without regard to the Suntunnels. He felt there would not be enough par to make much difference and he mentioned the fitered uv as being a downfall. One can argue the fact that others have tanks that are quite bright with the tubes and corals seem to flourish. On the other hand Anthony is the great coral guru and knows a lot about growing them under natural sunlight.
To answer your question I would put one tube on each side to make the light even on each side. Also you should extend the tunnel shaft through the ceiling to just above your tank. If you build up the canopy and have the light shine into it with the halides I think the light will be lost among them. I think the light needs to be focused above the surface of the water to penetrate it to a significant extent.
One more thought is you can't compare them to bulb watts, even if you convert incandescent to halide output (there is a conversion chart somewhere). You need to first consider how long the tubes are, how many bends, what direction they face, time of day, time of year, your latitude etc.... Once again a light meter would be most useful here.