Pure Sunlight over your tank

[furyclown]

Tell me I'm crazy......


Due to minor hail damage we are having our roof replaced, less the deductible. I was thinking about one of those Solatubes over the fish tank.
You might have seen them in the Parade Magazine in the Sunday paper.

14" across, like a small skylight but, with reflectors, in a vacuum tube.
What about, if one was installed directly above the fish tank, perhaps with a reflective tube, that telescopes up, for access to the fish tank.

The roofer is quoting me $350.00 for the Solatube, (regular ceiling mount)
of course there would be more for the extension down to the aquarium.

I was thinking, maybe, I could save $$$ in lighting over the long run....

What do you think?

 

[Anonymous]

All the tanks I've seen utilizing direct sun, usually have supplementary lighting. Even in HI they use mh's in conjunction with natural lighting. It is some what dependant on your location, I'm in SF bay area in CA and I've had a few outdoor tanks, all had to have extra lighing for winter months and reduced extras for summer. I always needed extra lighting, except when just growing lower light loving corals.

 

[furyclown]

That's amazing!

Why would our corals require more than nature ?

 

[Anonymous]

Well, you don't really live near the equator, right?

I guess it all depends on how often the sun is out in your area and how intense the sunlight is. Isn't the sun extremely more intense on the equator?

For example, I live in Southern California, but I am on the beach and it's foggy here about 40% of the time. I'm pretty sure any corals I have would suffer because of that. If the sun is out most of the time there in Texas, then I would assume your corals would do very well with natural sunlight. But I'd keep the halides installed anyway, for cloudy days and such.

 

[Anonymous]

Thought I might also mention that even though they would have easy access to natural light, I've never seen a public aquarium use it on their reef displays. They've always used halides. There must be a reason.

I think the suggestion of using natural in conjunction with halides and/or VHO/CF would be the way to go. I think you'd still save money in the long run, and it would be a very interesting experiment to see the corals' reaction to living under natural sunlight.

 

[Ken2001]

One other factor to remember is that the solotube will not give a full spectrum of light to your tank. You'd have to somehow check to see what part of the spectrum is filtered out by the skylight's window pane (Plexiglass?) and suplement that. Also, if your roof is angled, so that the section of the roof with the skylight is only getting full sun part of the day, it won't be the same as the water surface on the reef that is getting all of the available sunlight throughout the day. And yeah, in Texas you're getting seasonal differences in available sunlight that wouldn't be seen on a reef on or near the equator.

Sounds like this might be a fun way to get some extra light, but not all that your reef will need.

Ken

 

[Anonymous]

Its not even close to more light than nature, unless your right on the equator, like mentioned, you'll have less light as the sun is further away. In Hawaii, like I mentioned, they use both real sun and mh on their Indo reef display because they aren't at the same intensity as Indo.
check out this link to a picture by James Wiseman- http://www.advancedaquarist.com/issues/ ... CF0012.htm
In Australia they used mh's outside on their Algael Turf Scrubbers. Montery bay aquarium even utilizes mh's for their local display in conjunction with natural lighting.

 

[wombat1]

I think you probably don't need the extension from the ceiling. The extra two feet or so is really not that much. I agree that the frosted glass most sunlights use is going to filter out a lot of light, so maybe you could use clear glass?? If this tank was for SPS corals, I would use supplementary MH in a pendant. If it's for mushrooms and button polyps you might be able to get away with no additional light.

 

[Anonymous]

nobody's mentioned, also, that outside of that 200-300mi range (north/south) of the equator, the sun's going to shine fewer hours during winter and longer during summer. equatorial regions are pretty much 12/12 (like in puerto rico, 200mi N - apprx), light at 6am, dark at 6pm.

i've seen the solatube advertised as well, but couldn't get them to send me any information! intensity can be measured using a photog's light meter, but as far as how "true" the color saturation and spectrum really are might be left to debate (UNLESS the manufacturer can give you good specs/stats/measurements on whatever material is being used, i don't think it's plexi or regular glass, though). which still leaves the issue of photoperiod. BUT, if you've got deeper reef specimens, who can say it absolutely won't work, eh? i mean, you probably couldn't keep clams and the like based on photoperiod alone, but there are other critters, yeah?

chrisgeo, you actually live ON the channel islands??? you military?

 

[dale nilson]

According to a prior thread, Solatubes are not very efficient. I can't figure out how to post the thread, but do a search on "solatubes" and you'll find it.

 

[Minh Nguyen]

How much light you get depends on the collecting area minus the in-efficency of the tube. Because these two factors, solar tube, IMO, only add a minor amount of light to the tank amily due to the aperture of only 14 inches circle.
Minh Nguyen

 

[furyclown]

Thanks to all for your input.

I thought there had to be somethings I wasn't considering.

And, my non-reef spouse thanks you too for not poking a hole in our ceiling.

 

[esmithiii]

i would be curious to hear what some of the people aquaculturing corals in greenhouses use for supplemental lighting (if anything.) A friend has a large greenhouse and I was considering setting up a natural sun lit grow out tank there. Anyone with experience on this?

Ernie

 

[O P Ing]

hi.
The issue of solatube came up almost once a month in various forums, and the conclusion is invariably not very good due to the lack of control and inefficiency (sorry for using this word for something like free sunlight). A large solatube is about as bright as a 250W MH during noon. During the rest of the day, it is even more dimmer. So you definitely need to supplement it with MH.

 

[SAT]

I have 3 21" solar tubes over my new (not yet running) 300G. They've been installed long enough so I have a pretty good feel for how they work.

First, let me address the spectrum issue: the dome is acrylic, which is darn near perfectly clear in the visible range. The walls are some sort of coated silver, which is an excellent reflector. The net effect is the light coming out of the bottom has a CRI of nearly 100, which is a whole lot closer to a natural spectrum than any man-made lamp.

The color temperature when the sun actually hits the dome will be about 5000K, which is a lot redder/oranger/yellower than is normal 30' under water. If you prefer the violet/blue look that many reef tanks sport, you can supplement with actinics or put a blue filter over it. On a cloudy day, or when the dome is shaded, the light is dimmer but has a higher color temperature.

Assuming the absence of clouds (and yes, there are clouds in the tropics), the delivered light intensity is determined by the diameter of the tube, how much light is absorbed in the tube, and the angle of the sun. I find that a pretty high percentage of the light that hits the tube actually comes out the bottom (my meter isn't highly accurate, but I think about 80% comes through). However, when the sun angle is low the usable light drops significantly because (a) less of the light enters the vertical tube and (b) the light comes out the bottom at the same angle it entered the top.

With three 21" tubes, I calculate they illuminate the area over my 8'x2' tank at a peak of about 36% of full sunlight. Averaged over the middle 6 hours of the day, it's probably more like 25%. That's actually not bad when you consider that the water over a typical reef absorbs quite a bit of light.

A 14" tube would illuminate a 20G tank (2 square feet) at about the same level as the 3 21" tubes illuminate my 300G. A larger tank will get correspondingly less benefit.

A concern is the period of peak intensity is only a few hours long. However, due to the reflectance of the water surface when the sun angle is low, that's actually very natural. Corals are used to high intensity for only about 4 hours a day anyway.

A bigger concern is what happens during the Winter. During the Spring and Summer, sunlight delivery here in SE Pennsylvania is nearly as high as in many areas of the tropics (the intensity is lower but the day is longer). However, during the Winter it is much less. Thus, any scheme based on daylight needs supplementation during the darker months.

I won't contradict the negative comments above. If you think a tubular skylight will solve all your lighting problems, you're wrong. However, it will allow you to (a) use smaller bulbs and less power, (b) improve the color rendition, and (c) reduce the amount of waste heat. Besides, you also get a true moon cycle. I say go for it.

 

[O P Ing]

hi.
It is always great to have someone who have actual experience with the setup. 8)

I was just trying to tell others that solatube as sole light source without supplement is not a very attractive idea, not discouraging other who have the resource to do it if they have the preference.

 

[ger]

I also played with the idea of using two solatubes in combination with MH lighting. I spoke with a very nice guy at the company that makes them but he said they never tested the light spectrum that makes it through the tube. However, he told me that the diffuser would be the most limiting factor. He thinks depending on the diffuser you may loose up to 80% of the sunlight intensity. The light that the tube distributes without one doesn't look that good and they only have so many options as diffusers, but I was thinking of having a concave lens made (if that is possible). What do you think?

 

[SAT]

However, he told me that the diffuser would be the most limiting factor. He thinks depending on the diffuser you may loose up to 80% of the sunlight intensity. The light that the tube distributes without one doesn't look that good and they only have so many options as diffusers, but I was thinking of having a concave lens made (if that is possible). What do you think?

Yes, the diffuser loses a lot of light. I'm just running a sheet of clear acrylic over the opening and allowing the light to come straight through. The tubes come into a box over the tank that's painted brilliant white, on the inside, so as much light as possible is redirected into the tank rather than into the room.

Bring the tubes down as close to the water as practical. That will be limited by the space required for access and for the supplemental lighting.

A concave lens could be interesting, but I suspect it's hard to make. Be careful not to focus the light too much... you don't want to fry your coral. :mrgreen:

Lighting a room without a diffuser doesn't look good. However, IMO, lighting an aquarium is interesing. You'll see a lot of constantly changing glitter lines caused by reflections in the round tube.

 

[O P Ing]

hi.
Since the critical angle of water and air is 48.75 degree, you can just put a clear container with water on the opening, and do away with a lense. Don't know how practical this will be, because of the weight of the water can be a lot more than a plastic lense.

Any light that shine on the water will go down the water column at no more than 50 degree from the vertical. So no matter how low is the sun, the light always shine down the tube at about 45 degree angle.

 

[SAT]

hi.
Since the critical angle of water and air is 48.75 degree, you can just put a clear container with water on the opening, and do away with a lense. Don't know how practical this will be, because of the weight of the water can be a lot more than a plastic lense.

Any light that shine on the water will go down the water column at no more than 50 degree from the vertical. So no matter how low is the sun, the light always shine down the tube at about 45 degree angle.

Interesting idea... the problem is you'll get the inverse effect when the light exits the bottom of the container. Assuming the container ends are flat, light will exit at its original angle.

You could, however, make a lens using the water and a convex or concave sheet of acrylic.