SolaTubes for reef tanks - Page 14

salty joe · 01/05/2005, 11:46 AM

The Velux brand skylight has an outstanding flashing kit. Normally they have a double coating of low E, which helps prevent heat loss but also cuts down UV. Hopefully, they are available in clear glass.

Would a 40" x 40" skylight with a polished aluminum plenum down to the tank provide less light than 4 21 inch tubes? If this is so, can someone please explain why.

I was thinking that maybe the solar panel industry would have the answer as to the exact orientation for a skylight in a given location to maximize light.

I am also very interested in the tracking panel. Any info would be much appreciated.

Shoestring Reefer · 01/05/2005, 12:36 PM

I would think that, everything else being the same, the amount of light would be proportional to the area of the opening. So I think that a 40" X 40" skylight would provide more than (4) 21" tubes. But I guess actual area would have something to do with it, and those might be nominal dimensions.

But, keep in mind: with a wider tube, the light has to bounce off the sides fewer times before it reaches the bottom. Fewer bounces = more light. So, if the reflectivity of the solar tubes and the aluminum duct were the same, you would get more light transmitted through the duct.

Ehydo · 01/06/2005, 09:01 AM

Actually that is not true. In a rectantular area there is less light transmitted because of the angles the light has to bounce. In a tube there are no corners or dead spots for the light to get diffused. Also in a tube when light hits a small spot the light reflected reflected is wider than the original beam and transfers to a bigger area allowing the light to concentrate.

It is called total internal reflection.

Shoestring Reefer · 01/06/2005, 09:06 AM

Ok, th ecorners make a bit of sense--I guess someone could try to fabricate rounded courners, that migh be a PITA. But I don't get what you mean by rounded surfaces reflecting more light, if that was what you were getting at.

Ehydo · 01/06/2005, 09:15 AM

It reflects in wider patterns, But there are limitations to the light travel.

Ehydo · 01/06/2005, 09:18 AM

In a tube it is easier to control how the light is coming into it. That allows you to control the direction of the reflected rays and the refracted rays. That allows you to get a higher useful percentage of the light entering the tube.

look here and do some theorizing

http://www.tulane.edu/~sanelson/geol211/proplight.htm

Shoestring Reefer · 01/06/2005, 09:55 AM

Was the link for general discussion? I couldn't figure out what it has to do with round vs square tubes; maybe that's not why you posted it?

The tube does not concentrate the light, it diffuses it--unless the sun is shining directly down the tube, in which case it still won't have any significant concentrating effects.

For example, imagine a skylight of a given area on a flat roof, and the sun hits it at a 45-degree angle. You end up with a bright, square patch the size of the skylight. But maybe not where you want the light. Next to it, place a verticle solar tube of the same area. Out of the solar tube, the light will spread at a 45-degree angle in all directions. So, you end up with a bigger but dimmer patch, but it's where you want it.

So, to sum it up, a solar tube won't concentrate the light more than a skylight (unless you taper it) it just puts it in a different location for you.

Ehydo · 01/06/2005, 10:21 AM

Are you comparing a standard skylight to a solar tube or a skylight with a reflective metal box on it like saltyjoe was saying?

Either way tou are going to get more light out of the solar tube because there is a parabolic lens on the end concentrating more light to start with.

So SaltyJoe if you have an equal circumference of a Skylight with a reflective plenum and a solar tube you will get more light our of a solar tube and you will not have to re-frame your roof.

Shoestring Reefer · 01/06/2005, 10:34 AM

Both. I was comparing the solar tube to the plain skylight to demonstrate the fact that it does not concentrate the light. About the "parabolic lenses": from what I've read here, those just use clear plastic domes, not parabolic lenses. Other manufacturers have similar information.

Out of curiosity-are you basing what you've been posting on manufacturer claims or some published data, or just what you thought up? An educated guess (which is what i 've been doing some of the time) is better than nothing when we don't have much else to go on, but it should be prefaced with something like "I think".

Ehydo · 01/06/2005, 11:38 AM

Mike, I totally agree with a plain plastic lens cap they would be no different. The concentrating of the light before it enters the tube is extremely important. Here is a link to the one that I was looking at. I looked at some others but this one is the most recent. http://www.toolbase.org/tertiary_pri...ocumentID=2024

wazbot · 01/07/2005, 06:46 AM

I'm having 4 solatubes put in my roof this coming wednesday if all goes to plan...

unfortunately my tank and stand are still being constructed, so it will be a while before I can post any real results or such.

I'm hoping I will get enough sunlight here in Perth, Western Australia, to not need MH, but we will see. I have a few spare kicking around so if i need to supplement, I will.

As soon as I have some happy snaps, I will post them

Wazbot

Ehydo · 01/07/2005, 08:37 AM

That sounds great wazbot. Get us some pictures. Most of this thread is talk and no pics.

salty joe · 01/07/2005, 09:12 AM

It's my understanding that you do not want UV protection when lighting a reef tank. Also, with a sun pipe I would think that the diffuser at the bottom of the pipe would be counterproductive.

gatohoser · 01/07/2005, 12:58 PM

Glass reduces UV (the kind u need to avoid) by a large percentage so unless this is a straight open tube, which i dont think it is although ive never seen it, i dont think that would be much of a problem.

wazbot · 01/12/2005, 08:59 AM

Okay, the day we have all been waiting for (well, me anyway)...

My 4 solatubes were installed today, no hitches at all.

The tubes themself are almost directly vertical, no significant bends (i'll try to get a photo of this), and the light was astonishing.

The installers had a lux meter with them, so I managed to get some readings before, during and after installation. All the readings were taken at midday, but I will be getting a lux meter myself tomorrow so that I can take some proper readings over the next couple of months.

Before installation, at the proposed water level of the tank (about 24cm, 10inches? below the lowest point of one tube), the lux was 160, once the holes had been cut in the ceiling and roof it rose to about 700, and then with the completed installation it hit 60000! Keep in mind it is mid summer here, with super clear blue skies. For reference the lux in full sun outside was at 105000.

I still need to remove some dust from inside the tubes with a duster on a long pole, so this may raise the lux a bit. Also, there is no difuser of any sort on the tubes, other than the acrylic dome on the roof, I was initially worried about the heat, but after sitting under it for 30 minutes I decided it wouldn't be an issue. If I am wrong, I can easily put a clear acrylic disc inside the tube to create an insulating air pocket (there are small brackets inside for the normal diffusers).

Anyway, here are the pics, zipped for your convenience!

wazbot · 01/12/2005, 09:06 AM

next photo, looking at the domes...

Shoestring Reefer · 01/12/2005, 09:11 AM

So, 4 for the tank and one for another room?

salty joe · 01/12/2005, 09:18 AM

Wazbot,
Nice, very nice. What is the diameter of your tubes?
What are you using the number five tube visible on the roof for?
Is your roof concrete tiles?
How far are you from the equator?
I can hardly wait to see how well this lighting scheme works.
Thanks for the pictures, please keep us posted.
Joe

wazbot · 01/12/2005, 09:18 AM

Yup, one for the 'fish room', it doesn't have an extension tube on it, but if decide to have a grow-out tank I can easily put one on.

All the plumbing for this tank is going through the big white brick wall into the 4m x 4m room behind.

Also the extension tubes are exactly 60cm (2foot?) from the ceiling.

here is a shot taken 2 minutes ago, its night so I needed the flash, looking up the tube.

wazbot · 01/12/2005, 09:26 AM

SaltyJoe: 24.5cm diameter tubes, maybe a growout tank in the future, but just to light the fishroom at this time, and yup, concrete tiles. My geography is crap, if someone knows how far Perth, Western Australia is from the Equator, please chime in. I do believe there are some coral species (poci's) on an island called Rotnest just off our coast, only 40min boat ride away, so who knows?

This is another photo of looking right up the tube, should remind some of you old fella's of that time they call the sixties!!

Ehydo · 01/12/2005, 09:37 AM

Let me help you out a little.

I kept asking for pictures.

wazbot · 01/12/2005, 09:50 AM

Thank you very much Erik!

I havn't got a webpage up yet, but will get one up in the near future.

I am itching for a full moon, only 2 weeks away. Can't wait to see how it looks.

When I look up through the tubes I can see the streetlights!

From outside they glow a dull purple/actinic from my reef tank a few feet away, I wonder what the neighbours think?

wazbot · 01/13/2005, 08:24 AM

Okay, I now have a lux meter, so tomorrow I will take some readings at various times, and post!

Almost forgot,

SaltyJoe: Perth is 32 degrees south of the equator

Ehydo · 01/13/2005, 08:31 AM

wazbot make sure you send me a PM with a link to your thread about setting up your solar powered tank...

I think that you could get a nice thread started about your setup.

salty joe · 01/13/2005, 09:17 AM

Are your tank dimensions metric? Or are those measured in feet?
If you are going to start a thread concerning your solar powered tank, why not post a link in this thread?
Anybody reading this thread is going to be interested to see how well your tank does.

01/05/2005, 11:46 AM	#326
salty joe Registered Member Join Date: Oct 2002 Location: medina, ohio Posts: 2,419	The Velux brand skylight has an outstanding flashing kit. Normally they have a double coating of low E, which helps prevent heat loss but also cuts down UV. Hopefully, they are available in clear glass. Would a 40" x 40" skylight with a polished aluminum plenum down to the tank provide less light than 4 21 inch tubes? If this is so, can someone please explain why. I was thinking that maybe the solar panel industry would have the answer as to the exact orientation for a skylight in a given location to maximize light. I am also very interested in the tracking panel. Any info would be much appreciated. __________________ Time to roll the dice.

01/05/2005, 12:36 PM	#327
Shoestring Reefer Registered Member Join Date: Jul 2003 Location: Westerly, RI Posts: 4,989	I would think that, everything else being the same, the amount of light would be proportional to the area of the opening. So I think that a 40" X 40" skylight would provide more than (4) 21" tubes. But I guess actual area would have something to do with it, and those might be nominal dimensions. But, keep in mind: with a wider tube, the light has to bounce off the sides fewer times before it reaches the bottom. Fewer bounces = more light. So, if the reflectivity of the solar tubes and the aluminum duct were the same, you would get more light transmitted through the duct. __________________ Mike Reefcentral Folding@Home team 37251 - Click my little red house to learn more and help medical science! Current Tank Info: 2, 20-gal low tech tanks

01/06/2005, 09:01 AM	#328
Ehydo Registered Member Join Date: Jul 2004 Location: Buford, Georgia Posts: 804	Actually that is not true. In a rectantular area there is less light transmitted because of the angles the light has to bounce. In a tube there are no corners or dead spots for the light to get diffused. Also in a tube when light hits a small spot the light reflected reflected is wider than the original beam and transfers to a bigger area allowing the light to concentrate. It is called total internal reflection. __________________ Erik Hydo Current Tank Info: 72 reef

01/06/2005, 09:06 AM	#329
Shoestring Reefer Registered Member Join Date: Jul 2003 Location: Westerly, RI Posts: 4,989	Ok, th ecorners make a bit of sense--I guess someone could try to fabricate rounded courners, that migh be a PITA. But I don't get what you mean by rounded surfaces reflecting more light, if that was what you were getting at. __________________ Mike Reefcentral Folding@Home team 37251 - Click my little red house to learn more and help medical science! Current Tank Info: 2, 20-gal low tech tanks

01/06/2005, 09:15 AM	#330
Ehydo Registered Member Join Date: Jul 2004 Location: Buford, Georgia Posts: 804	It reflects in wider patterns, But there are limitations to the light travel. __________________ Erik Hydo Current Tank Info: 72 reef Last edited by Ehydo; 01/06/2005 at 09:30 AM.

01/06/2005, 09:18 AM	#331
Ehydo Registered Member Join Date: Jul 2004 Location: Buford, Georgia Posts: 804	In a tube it is easier to control how the light is coming into it. That allows you to control the direction of the reflected rays and the refracted rays. That allows you to get a higher useful percentage of the light entering the tube. look here and do some theorizing http://www.tulane.edu/~sanelson/geol211/proplight.htm __________________ Erik Hydo Current Tank Info: 72 reef

01/06/2005, 09:55 AM	#332
Shoestring Reefer Registered Member Join Date: Jul 2003 Location: Westerly, RI Posts: 4,989	Was the link for general discussion? I couldn't figure out what it has to do with round vs square tubes; maybe that's not why you posted it? The tube does not concentrate the light, it diffuses it--unless the sun is shining directly down the tube, in which case it still won't have any significant concentrating effects. For example, imagine a skylight of a given area on a flat roof, and the sun hits it at a 45-degree angle. You end up with a bright, square patch the size of the skylight. But maybe not where you want the light. Next to it, place a verticle solar tube of the same area. Out of the solar tube, the light will spread at a 45-degree angle in all directions. So, you end up with a bigger but dimmer patch, but it's where you want it. So, to sum it up, a solar tube won't concentrate the light more than a skylight (unless you taper it) it just puts it in a different location for you. __________________ Mike Reefcentral Folding@Home team 37251 - Click my little red house to learn more and help medical science! Current Tank Info: 2, 20-gal low tech tanks

01/06/2005, 10:21 AM	#333
Ehydo Registered Member Join Date: Jul 2004 Location: Buford, Georgia Posts: 804	Are you comparing a standard skylight to a solar tube or a skylight with a reflective metal box on it like saltyjoe was saying? Either way tou are going to get more light out of the solar tube because there is a parabolic lens on the end concentrating more light to start with. So SaltyJoe if you have an equal circumference of a Skylight with a reflective plenum and a solar tube you will get more light our of a solar tube and you will not have to re-frame your roof. __________________ Erik Hydo Current Tank Info: 72 reef

01/06/2005, 10:34 AM	#334
Shoestring Reefer Registered Member Join Date: Jul 2003 Location: Westerly, RI Posts: 4,989	Both. I was comparing the solar tube to the plain skylight to demonstrate the fact that it does not concentrate the light. About the "parabolic lenses": from what I've read here, those just use clear plastic domes, not parabolic lenses. Other manufacturers have similar information. Out of curiosity-are you basing what you've been posting on manufacturer claims or some published data, or just what you thought up? An educated guess (which is what i 've been doing some of the time) is better than nothing when we don't have much else to go on, but it should be prefaced with something like "I think". __________________ Mike Reefcentral Folding@Home team 37251 - Click my little red house to learn more and help medical science! Current Tank Info: 2, 20-gal low tech tanks

01/06/2005, 11:38 AM	#335
Ehydo Registered Member Join Date: Jul 2004 Location: Buford, Georgia Posts: 804	Mike, I totally agree with a plain plastic lens cap they would be no different. The concentrating of the light before it enters the tube is extremely important. Here is a link to the one that I was looking at. I looked at some others but this one is the most recent. http://www.toolbase.org/tertiary_pri...ocumentID=2024 __________________ Erik Hydo Current Tank Info: 72 reef

01/07/2005, 06:46 AM	#336
wazbot Premium Member Join Date: Feb 2003 Location: Western Australia Posts: 46	I'm having 4 solatubes put in my roof this coming wednesday if all goes to plan... unfortunately my tank and stand are still being constructed, so it will be a while before I can post any real results or such. I'm hoping I will get enough sunlight here in Perth, Western Australia, to not need MH, but we will see. I have a few spare kicking around so if i need to supplement, I will. As soon as I have some happy snaps, I will post them Wazbot __________________ Wazbot Current Tank Info: 2500L Reef

01/07/2005, 08:37 AM	#337
Ehydo Registered Member Join Date: Jul 2004 Location: Buford, Georgia Posts: 804	That sounds great wazbot. Get us some pictures. Most of this thread is talk and no pics. __________________ Erik Hydo Current Tank Info: 72 reef

01/07/2005, 09:12 AM	#338
salty joe Registered Member Join Date: Oct 2002 Location: medina, ohio Posts: 2,419	It's my understanding that you do not want UV protection when lighting a reef tank. Also, with a sun pipe I would think that the diffuser at the bottom of the pipe would be counterproductive. __________________ Time to roll the dice.

01/07/2005, 12:58 PM	#339
gatohoser Registered Member Join Date: Sep 2003 Location: Monterey, CA Posts: 1,490	Glass reduces UV (the kind u need to avoid) by a large percentage so unless this is a straight open tube, which i dont think it is although ive never seen it, i dont think that would be much of a problem.

01/12/2005, 09:11 AM	#342
Shoestring Reefer Registered Member Join Date: Jul 2003 Location: Westerly, RI Posts: 4,989	So, 4 for the tank and one for another room? __________________ Mike Reefcentral Folding@Home team 37251 - Click my little red house to learn more and help medical science! Current Tank Info: 2, 20-gal low tech tanks

01/12/2005, 09:18 AM	#343
salty joe Registered Member Join Date: Oct 2002 Location: medina, ohio Posts: 2,419	Wazbot, Nice, very nice. What is the diameter of your tubes? What are you using the number five tube visible on the roof for? Is your roof concrete tiles? How far are you from the equator? I can hardly wait to see how well this lighting scheme works. Thanks for the pictures, please keep us posted. Joe __________________ Time to roll the dice.

01/12/2005, 09:37 AM	#346
Ehydo Registered Member Join Date: Jul 2004 Location: Buford, Georgia Posts: 804	Let me help you out a little. I kept asking for pictures. __________________ Erik Hydo Current Tank Info: 72 reef

01/12/2005, 09:50 AM	#347
wazbot Premium Member Join Date: Feb 2003 Location: Western Australia Posts: 46	Thank you very much Erik! I havn't got a webpage up yet, but will get one up in the near future. I am itching for a full moon, only 2 weeks away. Can't wait to see how it looks. When I look up through the tubes I can see the streetlights! From outside they glow a dull purple/actinic from my reef tank a few feet away, I wonder what the neighbours think? __________________ Wazbot Current Tank Info: 2500L Reef

01/13/2005, 08:24 AM	#348
wazbot Premium Member Join Date: Feb 2003 Location: Western Australia Posts: 46	Okay, I now have a lux meter, so tomorrow I will take some readings at various times, and post! Almost forgot, SaltyJoe: Perth is 32 degrees south of the equator __________________ Wazbot Current Tank Info: 2500L Reef

01/13/2005, 08:31 AM	#349
Ehydo Registered Member Join Date: Jul 2004 Location: Buford, Georgia Posts: 804	wazbot make sure you send me a PM with a link to your thread about setting up your solar powered tank... I think that you could get a nice thread started about your setup. __________________ Erik Hydo Current Tank Info: 72 reef

01/13/2005, 09:17 AM	#350
salty joe Registered Member Join Date: Oct 2002 Location: medina, ohio Posts: 2,419	Are your tank dimensions metric? Or are those measured in feet? If you are going to start a thread concerning your solar powered tank, why not post a link in this thread? Anybody reading this thread is going to be interested to see how well your tank does. __________________ Time to roll the dice.