SolaTubes for reef tanks

[chask]

Herpervet wrote:
What you have is multiple point sources of light and very odd shapes. Many of the "beams of light" are semicircles.

They change continually as the sun moves so each hour the light comes in from a slightly different angle.

The effects are most dramatic when there is no diffusion lens but simply a clear acrylic lens.

If a prismatic diffuser is used then the effect would be muted quite a lot.

Is there any loss of light intensity, spectrum (any of the the important parameters for the fish and corals) with the diffusers?

I am also curious about Fursphere's question regarding the use of acrylic.

Thanks
Charles

 

[gatohoser]

I am not sure it was this thread but i think it was discussed in this thread before. No time to check for you guys but maybe take a look over the last few pages.

 

[chask]

Yeah, I remember reading something about this before (and I also can't remember whether it was here or in another thread and cannot check right now) but I am not sure it was quantified. I seem to remember mention of the removal of the UV filter for coral health and someone suggesting an alternative that one of the manufacturers could use instead of the normal UV filter. I was kind of hoping that someone now had some more concrete info on this - like the diffuser cuts out 20 to 30% of the light output, or the removal of the UV filter and replacement with a non-UV filter will cause your acrylic tank to get brittle and crack.

Thanks
Charles

 

[Ehydo]

That is a bold statement:

"the removal of the UV filter and replacement with a non-UV filter will cause your acrylic tank to get brittle and crack"

You do alot of lighting studies?

Do you forget the fact that the water is absorbing some of the rays.

if you want to filter UV get OP3 acrylic.

And Metal halides produce a bunch of UV. http://www.masla.com/reef/uvlighting.html

 

[Fursphere]

That article gives no information on acrylic and UV.

 

[DgenR8]

That is a bold statement:

"the removal of the UV filter and replacement with a non-UV filter will cause your acrylic tank to get brittle and crack"

You do alot of lighting studies?

I think if you go back and read his post again, you'll see that you took that the wrong way.
I could be wrong, but I think what Chask meant was along the lines of "I wish someone could give us something factual, even if it were along the lines of........"
I didn't read that as if he were making a statement we were supposed to take as fact.

 

[Fursphere]

No kidding!


Next time quote the whole sentence, not just the part you choose to read.

I was kind of hoping that someone now had some more concrete info on this - like the diffuser cuts out 20 to 30% of the light output, or the removal of the UV filter and replacement with a non-UV filter will cause your acrylic tank to get brittle and crack.

 

[Ehydo]

The article was not meant to give information on Acrylic. It was for the UV Part.

Example for researching:

Metal halides VS sunlight-> metal halides over acrylic tanks-> Metal halides yellowing tanks-> sunlight yellowing Acrylic ->

You get the idea.

Also almost all current Acrylics used today offer a 10 year anti-yellowing from sunlight exposure.

You need to ask the manufacturer of the tank to see what kind of Anti-yellowing warranty they have.

http://www.customaquarium.com/company.htm http://www.customaquarium.com/why_acrilic.htm
http://www.herbsnbirds.com/fish_tanks.htm
http://www.casco-group.com/whyacrylic.html
http://www.tapplastics.com/shop/product.php?pid=334&

This one does not mention yellowing but does mention a lifetime against cracking
http://bcreef.com/warrant.html

 

[gatohoser]

You know as for UV:
People don't ever talk about this but long-wave UV light (just below the visible spectrum down to what I'd guess is around 340nm) is actually more beneficial to photosynthesis than green light or some colors of red.

Just an afterthought on the subject...

 

[Acrylics]

Isn't there a potential problem with this and acrylic tanks?

Doesn't he UV rays of the sun weaken / cause acrylic to become brittle over time?

Fursphere & others,
In response to this, the answer are mixed: No, there is no potential problem with Solatubes but UV rays can cause a photochemical reaction over time but how much time are we referring to?
UVB, wavelengths in the 290-315nm range do cause a photochemical reaction in plastics and many other synthetic materials which can, over time, lead to material degradation. The actual amount of degradation will depend on may things including actual wavelength(s), intensity, and agle of incidence. That said, most mfrs of acrylic sheet will warranty their materials not to yellow or become brittle for a period of 10yrs (or more) due to naturally occurring UV radiation - meaning UVA and UVB. UVC is not exactly "naturally occurring" at the Earth's surface and is not dealt with at all in Dana's article at the Masla site listed above so there is little info insofar as UVC transmission by MH or other HID bulbs but my personal feeling as that litte to none is transmitted.

Normal, standard acrylic will absorb aright around 92-95% of all UV (per Sanjay IIRC) and will transmit nothing below 345nm so no UVB is transmitted by standard or UV filtering acrylic at all. Therefore, the outer "shell" or skylight component of Solatubes will absorb all of the radiation below 345nm so none of the UVB radiation can reach your tank anyway.

Years ago, this (acrylic yellowing) was a different story. Due to the molecular binders that were once used, the acrylic would begin to yellow due to UV radiation but this is not really the case anymore - at least for practical purposes as the material chemistry changed oh about 15 yrs ago

The above is from memory but there are papers to back it up at Cyro's website, look for papers on light transmission and you'll come up with stuff

Hope this make sense and answers a few questions,

James

 

[Fursphere]

Thank you.

 

[chask]

Ehydo - First, please consider that I am new to this and therefore ask a lot of amateurish questions in hopes of learning and therefore learning from your all's mistakes. Like my signature below says - dang if i no. BTW - thanks guys for paying for my mistakes, or at least the ones I am able to avoid because you guys have lead the trail on the bleeding edge.

Yes, as the others seem to have pointed out, I was asking a question about the potential damage that might be caused by UV to acrylic material. Furshpere had asked/commented about the unusual angles that the light from the solar tubes/skylights would be entering the tank having the potential to cause damage to acrylic tanks. I recall from earlier in this thread (I think) someone mentioning that many of the diffusers used by solar tube mfgs blocked all UV to protect furnishings. Most people don't want thisUV for that reason, but from the responses here UV is an essential for corals and someone suggested removing those filters/diffusers.

When Fursphere asked about UV damaging acrylic it set off big alarms for me. I am in the planning stages of a very large tank (1000-1500 gallon) that will most likely be made of acrylic. We are going to wait until a wall is opened up for a door to bring the thing in. It will not fit any other way. Therefore this is sort of a permanent thing and finding out that the lighting method I hope to use might cause the walls of the tank to break down is a bit disconcerting to say the least. So I was kind of asking if UV would damage acrylic not stating it would. Oh, and no I have never done any lighting research though I was an honors student in atomic physics and made the dean's honor roll because of it. Actually blew the curve terribly, 100 on every test.

James - I appreciate the info but it seems a bit inconclusive. Do acrylics break down after 10 years? What's the track record? Am I risking anything over the long term? Are there grades that are more suitable for longer term resistance? Is there anything that can or needs to be done to prevent acrylic from becoming sufficiently brittle to be a problem, or does it at all?

Thanks
Charles

 

[Acrylics]

Charles,
There is no "trigger" that at 10 yrs the material will become yellow or brittle This is just a warranty period. One must remember that the aquarium industry is a very small segemnt of the acrylic industry as a whole. A larger part is in windows and signage. If the material can withstand the UV radiation these things will take under direct sunlight, all day, every day, and still be warranted for 10 yrs - I think the little that it will get in home use, through Solatubes, is rather insignificant.

Your concerns are not take lightly, this is a rather large investment and you want to avoid any mistakes - this is completely understood and appreciated. I know you don't know me, but I ask that you trust that in all my professional career building these things for homes, restaurants, and public aquariums, not once have I ever heard of any of the newer (1990 or so on) acrylic tanks yellowing or becoming brittle. The worst I've seen has been material (not tanks) subjected to direct X-radiation and this material still does not just fall apart.

There are UV filtering materials but their inherent color (yellow - amber) makes them unpleasant to the eye though they have become better in recent years, Polycast UF95 being a prime example which has a slight tint to it but not *really* obvious.

Take heart that almost every public aquarium uses acrylic for their tanks and would not invest the millions of dollars and open themselves to the liablity if there was any significant indicator that the material would fail due to normal (even outdoor) UV exposure.

Hopefully this comes accross as intended, while your concerns are quite valid - there really is no cause for alarm.

James

 

[chask]

Acrylics - You are right about the large investment. Perhaps you don't remember but we spoke once a few months ago about a tank. I was impressed with your candor and, most of all, the amount of time you spent on the phone with me. It was quite an education and much apprecitated. And when I posted my last questions I sort of figured you would reply pretty soon. I realized most of what you said about businesses and public aquariums but also thought that they are more capable of recognizing a potential problem and, with their experience and easy access to their tanks, would be in a position to correct it. This will not be so in my case.

Anyway, thanks for the info. I will be sleeping easier this evening, or at least not falling asleep figuring out how to do all this differently.

Oops! Was that a little heracy here - not thinking about reefs morning, afternoon, night and in my sleep?

Charles

 

[delnino]

Just reiterating some info I posted much earlier in the thread. I spoke with Calfo at a reef club meeting and asked him about using tubes for corals. He stated that 80% UV blockage is about ideal for coral growth. He said that in his experience the cheaper the better for skylights as they let more UV transmit. This indicates to me that the domes on all available skylight tubes block to much UV (95-98%). Not sure about regular skylight plastics. Using unmodified tubes will not damage acrylic aquariums. Putting your tank outside for 10 years, maybe. The solution could be to have custom domes constructed out of more UV transmitting material. Of course then your curtains might fade. Maybe some supplemental UV lighting is the best solution. I think Anthony probably knows what he is talking about due to all his greenhouse experience. Can't wait to see this work. I love saving power...skylights, surge tanks, penductors, light movers, geothermal cooling, gravity fed skimmers etc.

 

[gatohoser]

I did not mean to say that you NEED UV light to activate photosynthesis in corals. Only that the highest spectrums of UV are particularly more useful than most spectrums of visible light excluding the humps around 420 and 660 nm and (according to some quick info from Bomber) depending on what corals plenty of other pigments will peak at other spectrums.

The only way i can see UV as being necessary is to produce anti-uv pigments (ak pigmented colors) in the coral for aesthetic value.

 

[delnino]

In their natural environment many creatures get bombarded with uv. Maybe they need it, maybe they don't? When a few of us get some solatube experience under our belts we will see. People from the future are going to laugh at us!!

 

[salty joe]

People from the future will thank you.

 

[chask]

Thanks delnino and gatohoser. Exactly the kind of information I was looking for. And I agree salty joe, people (at least those who like to do the reef thing) will thank us if this really works well. Or then maybe delnino will be right and they'll think we were off our rockers for even trying it. I can't help but think that anything that makes it cheaper to reef will be a boon to the hobby, and saving all that electrical power won't hurt at all either. That's better for everyone.

Charles

 

[corro]

Great thread. Does anyone have more tank pics of tanks with solatube lighting ... esp corals and/or coral colors. Specifically SPS. thanks!