SolaTubes for reef tanks

[Scuba_Dave]

Next year for me, after I see how much light I'm getting thru the 14" tube I just installed (still have to finish up the inside)
-not for a tank (well not yet)

[fishylongstocking]

Ill tell you one thing this really would be great for cutting energy costs! However it just is not practical for all areas. Here in the northern states we get a fraction of the amount of sunlight you folks in Arizona get.

Also a Aquarium is a closed system and even with the utmost care for nutrient quality you could get a massive algae outbreak if you have too much light. It is absurd to compare the natural reefs of fiji and australia to ones tanks, they have billions of gallons of sea water dilluting even the slightest pollution, hence very little algae.

[Shoestring Reefer]

If you have "too much light" you could always add a shade.

To learn more about "billions of gallons of sea water dilluting even the slightest pollution", check out the Responsible Reefkeeping Forum.

[fishylongstocking]

Mike,

I only intended to point out that these things are not for all and they are not perfect for newbies who dont have a lot of patience and will run out and buy these thinking they are the ultimate end all solution.

[Shoestring Reefer]

Ok. It looks like a major investment, so I never really thought of it as a newbie item, but who knows...

[Fursphere]

Is it really a major investment though? Three 9" tubes will run you approx ~$1000. (DIY install).

Then, once you work the bumps out, you get free lighting, perhaps free forever.

The cost of a high end lighting system can run $500 - $1000 pretty easy, then factor in the bulb replacements, and the cost of electricity.

In a year or two, the tubes will pay for themselves, maybe even a shorter time frame.

The only drawback I see is cutting a hole in your roof is a permanent thing (well, it could be patched up.. ya..), so something like this would best benefit a permanet tank solution, like an inwall setup or something.

Other than that, I don't see any drawbacks....

[hammerhead_77]

Along the same lines, I have been experimenting with using Fresnel lenses to concentrate a large area of natural sunlight into a smaller tank area to simulate the equatorial sun. It is amazing what natural sunlight can do!

[Shoestring Reefer]

Originally posted by Fursphere
The only drawback I see is cutting a hole in your roof is a permanent thing (well, it could be patched up.. ya..), so something like this would best benefit a permanet tank solution, like an inwall setup or something.

Yeah, that's what I was thinking of.

Hammerhead-
Details? Ie, where did you get your lense, do you have a light meter to compare sunlight vs the light you have focused, lessons learned?

[Fursphere]

I wish there was more information on this subject.

Lots of speculation and discussion about the subject in this thread, but very little (if ANY, besides just pictures of some guys tank in Austrailla with zero information) real world results (i.e. reefers who have actually installed systems over there tanks).

I'm in the process of constructing a 325 gallon inwall display tank myself, and I think my system would be a great canidate for this type of setup, and the proposed long term cost savings is really tempting. But I don't want to be the "guinea pig" here if you know what I mean.

[sharkdude]

none of the 'historic' pics in this thread still seem to displayed?

this thread has a pic from Dr Mac and Sons and I posted in his forum asking for results, but no reply yet.

http://reefcentral.com/forums/showth...8&goto=newpost

[hammerhead_77]

You can get a 2 meter x 2 meter flexible plastic Fresnel for $17. I have the supplier's website on my machine at home. They have lenses that will focus or that will columnate. I have a partner who is into things like measuring photon desity and such, but it is easy to see that 36 sq feet of sunlight focused into 16 sq feet of water surface area is pretty intense. So far I am mostly concerned with getting a constant temp. I'll report results once I have things going for a month or so.

[Shoestring Reefer]

Ok. Keep us posted.

[sharkdude]

http://www.edmundoptics.com/onlineca...productid=2040

They have high transmission % at the wavelengths we are interested in, but how could you adapt something like this to the dome of a sola tube?
I've heard of frensel lenses in Light houses before but I'm familar with their use for optical light collection.

[Shoestring Reefer]

Hmmm...those are a bit on the spendy side. I'd go for the $17 lense if possible-and if I had a house.

As far as mounting it: the lense will be wider than the light tube (that's the whole point in using it) and has to be above the tube by as much as it's focal length, so I guess you'd have to build a box above the solar tube, and mount the lense at the top of the box. Then put a weather-proof cover (like a dome) over it.

I wonder: when the sun is NOT shining down perpindicular to the lense'e surface, the light won't hit the center of the light tube. You could have a reflective cone-shaped adapter between the lense and the tube, but the "cone" shape means that light will be relfected OUT at low angles. So, you'd get more PEAK light for a gives size tube, but a shorter photoperiod. Plus the box, cone, and lense, and a bigger weather-proof cover. I can see the benefit when ducting light to the first floor of a two story house (because with a bigger tube size you would have to cut and sister floor joists) but I wonder how much the cost would compare to just cutting rafters and using a bigger tube in a 1-story home (ie, can work in the attic, don't have to rip up ceeling when sistering joists/rafters).

[hammerhead_77]

My partner and I are working on an out-door, earth bermed 4' x 4' x 3' plastic tank with a rectangular stand to hold the lense above the tank. The lense is flexible plastic, comes rolled up in a tube and is very similar to the wide-angle, stick-on thing you see in the back window of minivans.

Sun tracking is on the list of future efforts, with the technology to slowly tilt the lense coming from the folks who supply solar power panels. BTW, for the winter we will try pushing water through a solar heater panel from a swimming pool.

[Fursphere]

So... anyone taken this idea off paper and into the real world yet?

[Harleyguy]

I haven't read this whole thread, so I'm sorry if this has been covered. What is the spread of these lights? My tank will be 96" long and 32" high. How many of the 10" tubes should I need?

[Zephrant]

Considering that the sun's light is almost perfectly parallel when it gets to us, the spread is the diameter of the tube, unless you use a diffuser.

IIRC the diffuser blocks a good portion of the light too. I have been thinking that some kind of a diffractive grating or similar might spread the light without blocking as much.

Zeph

[Fursphere]

Cromed egg crate maybe?

[Shoestring Reefer]

My 0.02:

I also imagine that the "spread" would depend on how high the tubes are above the water's surface. Light enters a window but still fills a room (for the most part). And the brightness will depend on the ratio of tube surface area to tank area. For example, when my club got a PAR meter, we measured about 1600 outside, and 260 a few inches below a 250-watt SE MH. To get the same lighting intensity as that bulb (in Connecticut), you would need the tube's area to total about 1/6 the tank's area.

So, for a 96" long X 30" wide tank, you'd need (96 X 30 X 1/6) = 480 in^2. For 10" diameter tubes, that's 7 tubes (6.1 tubes, but I rounded up). That's IF you have 100% light transmittal, and IF you want a lighting intensity equal to one of those bulbs, and IF you only want that much light during noon (peak times).

But that's all an educated guess, my 0.02 and input appreciated.

[delnino]

I just installed a few tubes but none over a tank yet. I have a tank planned for my kitchen with tubes. $1000 for 3 tubes is way too much money. I bought 'natural light' tubes, $220 for each 13 inch kit from altenergystore.com. This is really a high quality product and I'm not easily impressed. Really easy to install if you have some basic skills, although takes me much longer than 2 hours like they say it will. I live in Denver and we get tons of sun but god damn these things are bright! I put them on a south facing roof. From 11 to about 3 you can barely look at them without blinding yourself and my ceilings are 11 feet. People that come over look up and then shield their eyes. I need to get a light meter and take some readings. I think tubes are more of a supplement to other lighting because of seasonal changes and limited hours. Moonlight really streams in even when not full, could be could for coral spawning and other biological rhythms in the tank. Having this type of lighting really connects you with the outside weather, my whole house changes each time a cloud passes over the sun.

[baja_01]

One other atvantage I see is the spectrum of natural lighting is smooth.

MH and other artifical lights are spiked in certain color areas to make the color of light.

[gatohoser]

Not to mention the spectrum would be 100% perfect.

[Herpervet]

Actually the spectrum may not be perfect for a couple of reasons.

The spectrum can shift as the light bounces down the tube according to one of the manufacturers I have spoken with in the past.

The other issue is that the color temp. of natural sunlight is not uniform. It is dependent on altitude and humidity.

The color temp at sea level and 80% humidity is significantly different than that at higher altitude and low humidity (which is my situation)

[baja_01]

The color may not be perfect, but I think if you look at a spectro graft(not sure if that is what is called) sunlight will have a smooth graft and artifical ligyht is spiked in certain areas to produce the light you see.

I just thought of another thing. Artifical light also flashes I think, the human eye can't notice it, but who know what could.

I am not saying that these will make huge differeces, but they are something to think about.