SolaTubes for reef tanks

[hllywd]

Salty, The thead is specifically about Solatubes and has been expanded to the large "square" skylight idea. My personal feelings are that the Solatubes are a better idea for the reason you stated although their collection area is limited. The one I installed is not over a tank but over the dining room table where my wife keeps a ficus tree during the months it can't be outside. In bright sunlight it offers a lot of light and it's directional nature isn't affected by the sun's changing position although it's intensity is. It provides about a 6' circle of light on the floor from the 8' ceiling, moonlight is also transmitted enough to light the table at night during the more "full" phases of the lunar cycle. It was very easy to install taking about an hour and a half to complete. I think the application, at least in NW Ohio, is supplimental lighting not a replacement for the artificial lights.

I also think if you can figure out how to make the 4 x 4 hole in the roof and maintain the roof's integrity, keep it from sweating and leaking, and focus the light on the tank, that is an even better idea but due to our winter length of day and timing you still wouldn't completely replace the artificial lights.

Unless somebody comes up with a revolutionary idea for this short of a heliostat and high quality mirrors for a system costing many thousands I'll continue to make my plans for the other $400 worth of Solatubes waiting in the attic for just such a project.

Tim

[hllywd]

Trickman, I installed 2 of the 14" Velux units in a condo I built an addition on this past fall. Installation isn't terribly invasive and you don't alter any structural components. Unless your association is different from how they work here you shouldn't have a problem.

Tim

[Trickman2]

Wish I could but I am a lower unit and have someone directly above me.

[salty joe]

Thanks for the reply Tim.

I understand that on a lot of applications, a flat roof for instance, a Sola tube will collect more light than a conventional skylight of comparable size.

I am thinking of a large skylight facing true south. From the solar panel industry, I found that the optimum angle is easily ascertained. Where I live it is approximately 45°. In this type of situation, I think any advantage from the Sola tube is negligible.

So back to my question. If the skylight is 4' x 4', and the aquarium is 4' x 18", how could using curved panels in the light tunnel yield more light than flat tapered panels in the light tunnel?

Joe

[barryhc]

Joe, it's just a matter of getting that 45 degree condition at the collector lense ( or skylight ) "turned" to match the "level" condition at the top of the tank. ( by way of curving the panels ) Also let's throw out any conception of "parabolic" here while we're at it, that was a poor choice of words, way back, on my part.

Also, the bottom portion of the mirror panels can be made to be more nearly parallel with each other so that the light is "funneled" more directly "down" into the tank, which reduces the amount of light that is able to "escape" through the tank walls.

I hope this is helpful. > barryhc

[barryhc]

I could make a little "graphic" thing, to illustrate, if you like.

Happy Reef Keeping! > barryhc

[salty joe]

Barry,

It would be great if light could be made to consistently hit the surface of the aquarium at a right angle. That seems like a mighty tall order considering that the sun does not stay in the same place. But maybe I'm missing something.

Yeah, I would appreciate it if you could post a picture.

By the way, light entering the surface of the water cannot escape directly through the glass of the aquarium. It has to be reflected off the rocks or fish or something first. I am pretty sure that there is a name for this phenomena , but I don't know what it is.

Joe

[barryhc]

Originally posted by salty joe
Barry,

It would be great if light could be made to consistently hit the surface of the aquarium at a right angle. That seems like a mighty tall order considering that the sun does not stay in the same place. But maybe I'm missing something.

Yeah, I would appreciate it if you could post a picture.Joe

Joe, I worked this up over the weekend, been real busy.



This works well here for a 12 x 12 pitch roof. I need better info. on seasonal and regional inclination to get more accurate, and look into accomodating seasonal variations.

The roof is considered to be pointing south here. I don't think we need tracking for the daily path of the sun.

A lot of good might be gained however for seasonal inclination differences. I would have to work on it more.

A lower pitch roof starts to make it a bit less advantageous for the curved panels, because of aspect ratios. I would need to work on more accurate values to see if any advantage could be made there.

By the way, light entering the surface of the water cannot escape directly through the glass of the aquarium. It has to be reflected off the rocks or fish or something first. I am pretty sure that there is a name for this phenomena , but I don't know what it is.

Well, that depends on the angle of incidence, and I haven't tested or researched that for specific values, but in the case of the skylight, this might be taken into account to improve morning and evening transferrence, with a two panel lense to improve incidence angle.

Let me know what you think.

Happy Reef keeping > barryhc

[cwloo]

Well, no matter solartube or skylight. The basic point here is to prove that it is workable to use Solar light as a reliable primary source of light to the reef tank.

I think we just need more picture, especially from senior reefer like SAT

[Trickman2]

I second the vote for Pictures.

[shookbrad]

Has anyone found any tubular skylights that have a dome the does NOT absorb the UV rays.
I wnat to install a few of these over my tank but I am not having any luck finding the domes I need.

[H20ENG]

Could you not just scrap the dome and use some framed starphire or other high UV transmittance glazing? The frame would be the skylight flashing.

I cant see the actual dome "catching" much more light than a flat pane.

Isnt the UV not really neccesary since most corals are several ft below the surface, which filters it out anyway?

[shookbrad]

Good question. I don't know. Anyone??

[barryhc]

Originally posted by H20ENG
Could you not just scrap the dome and use some framed starphire or other high UV transmittance glazing? The frame would be the skylight flashing.

I cant see the actual dome "catching" much more light than a flat pane.

Isnt the UV not really neccesary since most corals are several ft below the surface, which filters it out anyway?

I think that the dome "catches" more light during "adverse conditions", like early and late in the day, and less than "optimum" at "high noon". Actually I'm quite sure of it. It also "mediates" latitude and seasonal variations in the same manner.

Where are these tanks where the corals are several feet below the surface?

> barryhc

[H20ENG]

What I mean is that on a reef, the corals are several feet below the surface, and the water will filter out some UV. How much UV do they really need in our tanks?

I'm sure this topic has been beat senseless elsewhere on RC

So is it an issue or not with the polycarbonate domes?

I can see how the prizms in the dome could catch some light at odd angles, I just wonder how much.

[barryhc]

I don't have the specifics right now, but if you read a lighting thread, it will be specificly stated, "do not use high intensity lights without a UV filtering lense".

There are two types of UV, A and B. One is much more allowable than the other, and good "UV lenses" take this into account.

Yes, they are many feet to 10's of meters deep in the ocean, but not in our tanks. Think about UV "sterilizers".

> barryhc

[H20ENG]

UV sterilizers use UVC light at 257nm and would kill anything exposed to it for enough time. This is why they are inside an opaque tube- NOT above the tank.

I know about the UV protective glass for the DE halides,and again I ask: is NOT ENOUGH UV an issue with the domes?

[barryhc]

Originally posted by H20ENG
UV sterilizers use UVC light at 257nm and would kill anything exposed to it for enough time. This is why they are inside an opaque tube- NOT above the tank.

I know about the UV protective glass for the DE halides,and again I ask: is NOT ENOUGH UV an issue with the domes?

Sunlight includes every wavelength of light in the spectrum, and the exposure time is 960 times as much as a UV sterilizer.

Std. polycarbonates do not filter UV to any significant degree, and the resulting exposure to reef animals would be dangerous. The "filtering" elsewise, starts at the surface of the water. We don't have enough water depth to reasonably mitigate this effect.

"Not enough", is most certainly not an issue.

> barryhc

[barryhc]

I understand that many animals benefit from "some amount" of UV, it is not "a lot". Unshielded sunlight at the depths that these animals are in our tanks is dangerous. Filtering is required.

> barryhc

[gatohoser]

That seems sort of an unsupported claim. UV light in the upper spectrums (UVA) activates photosynthesis. UVB you do not want but 12 inches of water will just about eliminate it. Polycarbonate blocks some of UVA and all of UVB. "Clear coated polycarbonate absorbs all UV below 380nm. The absorptive pigments are in the clear scratch resistant coating."
http://aboc.8m.com/4.html

UV blocking lenses are required on HQI lights because they produce large amounts of UVB as well as even UVC which is mutagenic and lethal. UV sterilizers WOULD kill anything in the tank were they exposed to it. Fortunately they only act on those organisms which pass through the tubing

[gatohoser]

As for if there is a deficiency of UV problem, I think experience would tell us no. Many of us use lights that are completely UV blocked and likely our corals are not getting UV but we still can keep them okay.

It seems like the dome serves a use though to gather light and you would want to use it.

[gatohoser]

And as for this extra transmitted UV being harmful, I doubt it since many corals actually are exposed to direct sunlight when the tides recede. Maybe some corals aren't gonna be big fans but I think if slowly acclimated from the bottom of the tank (12" or deeper) they will get the required UV blocking pigments.

[gatohoser]

Oh and UV light adds some cool fluorescent pigments to corals (and shows them off too).

[barryhc]

Originally posted by gatohoser
And as for this extra transmitted UV being harmful, I doubt it since many corals actually are exposed to direct sunlight when the tides recede. Maybe some corals aren't gonna be big fans but I think if slowly acclimated from the bottom of the tank (12" or deeper) they will get the required UV blocking pigments.

Thanks Gatohoser, I think we have been stating the same things in the last couple of posts. Uncoated Polycarbonate does not have this protection and I can't say what coatings "Sola Tubes" have, but I don't think that there is much reason for it in normal Sola-Tube installations.

I think that many corals could be hampered severly by this UV light, when distances are short, like under 12" vaguely, but you have probably researched this more than I.

For std. Sola Tubes this would be a good bit less of a problem, than when you put 8-12 times "natural sunlight", by way of skylight "concentrating".

Reef Lighting has not been on the "top of my list" lately, looks like I should "brush up" a little bit.

Thanks, > barryhc

[JMBoehling]

I'll chime in.. I researched Tubular Skylights quite a bit before deciding to install them over my tank. A number of fellow hobbyist stated that it couldn't be done because of "Heat" from the sun. Well the UV resistant dome prevents a lot of the radiational heat from making it to the tank. Actually, there is very little heat transferred. I probably wouldn't attempt to replace the Dome's with Non-UV inhibiting glass or domes. Just my .02 cents..

later,

Jim