anyone actually know anything about light?

[aaron]

I have a question for a scientist who actually knows about light / solar radiation:

My friend has a coral farm in Sydney in a glass house. The light that originally came into the greenhouse through the clear roof was absolutely off the charts, far too intense for corals that are used to living in aquariums lit by artificial light. The current solution has been to paint white lime on the glass to block and defuse some of the light and this is working fine but we were wondering if it would be more beneficial to cover the glass roof in some kind of actinic blue film. and this leads me to my actual question:

Would such a film be blocking other colours in the light spectrum allowing more in the actinic range to get to the corals, or does the blue film actually absorb the blue spectrum, which is why it appears blue to our eyes?
I would be interested to hear from anyone with natural light aquarium experience or a background in this kind of thing.

 

[mray]

Blue film absorbs every color except blue which is why we see it as blue.

 

[Marteen]

From what I've read about natural light aquariums you should shade your corals for a few weeks to months initially but they will eventually adjust to the natural light.

 

[TimberTDI]

From what I've read about natural light aquariums you should shade your corals for a few weeks to months initially but they will eventually adjust to the natural light.

Marteen, I'm going to imagine that Aaron's friend is propagating corals to sell. If this is the case adjusting the corals to natural light could be detrimental when it goes back under artificial lighting.

Aaron,
You're probably going to have just do some trial and error and see what works best. Remember that most color films only allow 35 o/o of the light through.

Steven

 

[sjsoto]

i use natural light. coming in from west, north west, and south west. now for summer months noticed light to intense at afternoon till close to sunset. to alleviate problem, i used thin white curtains to cover windows, they are extremely thing since i still want to let some light in, and with designs with holes to let some in without being covered by curtain.

do you have any pics of the glass house?

 

[prattreef]

Aaron, I'm sure Sanjay can answer this for you in a fair amount of detail, but you will have to wait until he returns from India and I'm not sure when that will be exactly as his dad just passed away. We are talking days to weeks, not more than that.

 

[aaron]

Thanks Randy, I was hoping Sanjay was around. That's too bad about his father.
It's no rush, just something we starting talking about a few weeks ago and I thought I would turn the question over to some one who actually knows what they are talking about.
My friend is propagating coral for use in his aquarium maintenance business, so they will return to MH lighting once they have grown out. Its currently winter here in Australia, so light levels are not as critical for at least a few more months.

 

[cali_reef]

I don't know anything about natural sun light, but I have seen two large outdoor prop systems in Southern California. Both needed to be cover with fiberglass roofing panels as the sun rays were too strong for the depth of the ponds\tanks the corals were kept.

 

[jejton]

There are a couple of threads on RC by coral farmers who set up here in the US and their trials with different solutions for your very problem.

 

[SevTT]

I think you might be better off with a neutral density filter than a colored one. That is, neutral grey film, or, heck, netting/screening of appropriate densities. That way, everything gets the full spectrum, just less of it.

 

[aaron]

We are currently working with the glass painted with a thin coat of lime and shade cloth over the tanks which gives us an acceptable light level, we were just wondering if we could tailor the lighting to deliver more useful light without blasting the polyps with 10,000 lux of direct sunlight.
I will go and look for the threads on RC and see where that leads,

 

[ClosetFishGeek]

You might want to reach out to Anthony Calfo...He is a master at coral propogation and has been doing so for decades...using natural light for most of the growout and than halides towards at the end in a "finishing" tank. He also used various shades to deal with the strength(to much) of the sun. This book is awsome....

This guy has forgot more info than most people know....lol.. He is a great guy that will talk with fellow reefers openly...

Good luck.

 

[aaron]

Thanks for that, I actually met Anthony once before at some event organised by the Brooklyn aquarium society. Your right he is really open and easy to talk to.
I am off to the coral farm today, If I remember, I will take the camera and post some pictures

 

[bad coffee]

I have a question for a scientist who actually knows about light / solar radiation:
Would such a film be blocking other colours in the light spectrum allowing more in the actinic range to get to the corals, or does the blue film actually absorb the blue spectrum, which is why it appears blue to our eyes?
I would be interested to hear from anyone with natural light aquarium experience or a background in this kind of thing.

Aaron,
Color light filters only let certain wavelengths through the media. So if you wanted to have blue light on the corals, you use blue filters. The filter absorbs the green and blue spectrums, letting only the blue light through. but remember, any light that's absorbed will be transfered as heat. Maybe not the best thing for a greenhouse.

There are a bunch of filter manufacturers that get used in theater. Here's one in AU. http://www.rosco.com/australia/directory/index.asp

If you found data that proves which wavelengths corals grow best at, you could chose the filter(s) that only let those rays through. Say if corals grew best at 430nm (actinic blue that you're talking about,) you could pick a filter that has a light peak around 430nm.

I think in this case, it would be a great experiment to do over a smaller home/research tank. The scale your friend wants to do for his business doesn't necessarily lead to experimenting.

Sevv is correct. What you want is ND filters. Something that will just 'dim' the light across the board. In this case, though, buying actual filters would not be so cost productive. You could spend about $6 per 22"x24" sheet to cover the greenhouse, or you could spend a couple of bucks on what you're planning with the lime and the shade.

White sheets/muslin over the glass would work as well. You could layer the material to get the thickness you want.

No matter what you do, I'd suggest a PAR meter to measure exactly how much light is hitting the tanks.

Let me know if you have any questions about what I've said. Most of this stuff is pretty basic to me from working backstage. I may have missed some really simple facts.

B

 

[SevTT]

We are currently working with the glass painted with a thin coat of lime and shade cloth over the tanks which gives us an acceptable light level

Actually, I think that's a fantastic way to do it, if a little labor-intensive since I'm assuming you have to repaint the lime every once in a while. Another method of getting a ND filter would be to smoke the greenhouse panes, assuming that they're glass -- but this can be a real PITA to do consistently.

Remember, any modification that you do to the light spectrum can only -lower- the transmitted amount of light of any wavelength. (Anal point of order: it is possible to convert one wavelength into another -- for example, in fluorescence -- but not in any way that's feasible on this scale.) So when you put on blue filters, you reduce the red, yellow, and green wavelengths, but you pass on the blue -- slightly reduced due to inefficiencies in transmission. So, unless there's a specific color of light you want to eliminate from the spectrum, colored filters are kinda pointless.

 

[LimeInTheSky]

I would second reading the Anthony Calfo book.

Greenhouses would be for resellers and I have no idea how electric light could be used for that and make money still. Be careful though. Acans won't go for $100/polyp for ever.

The real question is after real light how does one go back to artificial light and sell a decent product. Apparently Calfo addresses this concern. I would be in favor of screens that could be adjusted but paint with white pigment would dissipate heat so that might be could too.