PAR readings from under the sun

[ouling]

Thought I'll start the tread and ask a few questions before the sun comes up.

I am going to test the PAR of the sun light in multiple different hours of the day.

I'm going to test the PAR under 1 ft - 18'' of water, also going to test the par for 24'' deep crystal clear salt water, under various hours of the day.

Anyone want me to do other tests while the PAR meter is with Ouling?:up:

BTW my tank is 17'' deep and the top of my water gets 1800PAR (lights 1'' off the water)!!!

 

[jeep9783]

Why?

 

[cdub]

it seems that he is testing the sun PAR so we can compare how our lights stack up against natural light.

i would also try to test while the sun is blocked by a cloud(maybe you can quantify rather it appears to be a thick or thin cloud)

 

[sprayin70]

Well I think this would be a great idea if we tested the sun from the part of the world that our corals are from. Good luck man!

 

[skriz]

Is there a reading at night with only the moon?

 

[sprayin70]

My buddy has a Lux meter and he measured the moon at 0 lux. He lives in Phoenix AZ. I have never tried Par though.

 

[photokid]

if the lux is 0 would the par not be 0 as well?

 

[jefft]

photokid;77604 wrote: if the lux is 0 would the par not be 0 as well?

:lol2: Lowest Par on most courses is 3. For the whole course the average is 72. :lol2:

 

[jefft]

Sprayin70;77596 wrote: Well I think this would be a great idea if we tested the sun from the part of the world that our corals are from. Good luck man!

If the club would pay for the trip I would be willing to travel to these places and test the PAR. I would make this sacrifice for the information.:yes:

 

[cgill311]

Try putting a powerhead in the tank to see if PAR is affected by turbulent water.

 

[wbholwell]

CGill311;77647 wrote: Try putting a powerhead in the tank to see if PAR is affected by turbulent water.

Good call, Chris. Aim the flow at the surface, so there are lots of ripples and surface agitation.

 

[skriz]

Any updates ouling?

 

[ouling]

still in class. Violent ripples on the surface will increase the par by 50-80%.

 

[FutureInterest]

You mean decrease? Hmmm... my surface water is always rippling.

 

[jmaneyapanda]

In the srpung/Delbeek book, they claim the "shimmers" actually focus the light and increase the intensity and PAR. Sounds a bit sketchy, but they do their homework.

By the way, I can save some time, our pathetic little lights are NOWHERE NEAR what the sun can do. Posting numbers will only bruise our egos.

 

[jeep9783]

what about 439 par at the bottom of my tank? That anywhere close?

 

[bzwaagstra]

How about testing with glass (usually salt encrusted) or egg create over the tank like many of us have. I suspect this will reduce PAR less with sunlight than with tank lights. I say this because, from a tank perspective, the sun is a line source not a point source (cause the point is much bigger than the tank). But it is just a guess.

 

[suasati]

jmaneyapanda;77706 wrote: In the srpung/Delbeek book, they claim the "shimmers" actually focus the light and increase the intensity and PAR. Sounds a bit sketchy, but they do their homework.

If you think about it, the shimmers are caused by wave motion, and the waves actually act like flexible lenses focusing light constantly shifting their focal point, you will get higher concentration of light on the lenses focal point, I am sure everyone have tried this as kids tryingto burn a piece of paper with a convex lens right...

NEAR what the sun can do. Posting numbers will only bruise our egos.

That is true, but I would think the wave length that penetrates 1-2' of water is much different from the one that reaches 20-40 feet.... par is not the only important factor here, what wavelength you suppy is also more important, the reason why you get algae blooms when you have sunlight falling on your tank...

 

[wbholwell]

SuAsati;77728 wrote: If you think about it, the shimmers are caused by wave motion, and the waves actually act like flexible lenses focusing light constantly shifting their focal point, you will get higher concentration of light on the lenses focal point, I am sure everyone have tried this as kids tryingto burn a piece of paper with a convex lens right...

One thing to consider is that to be able to focus light, the original light source must be be as close to a point source as possible. This is why we don't get shimmer from PC's or florescents.

I have a feeling that your average PAR over time is nearly the same, though. If you have convex-like waves that focus the light, you'll also have concave-like waves that disperse the light. I think the real benefit are those brief bursts that allow the light to penetrate deeper into the tank than it normally would.

 

[george]

Sprung and Delbeek do point to that as a possible effect and that the variations may help with animals the same way that seasonal lighting variations help.

However there's no such thing as a free lunch when it comes to energy transmission, so for every focused and intense "shimmer" there must also be an opposite "shade shimmer" in the water. I'd think the only benefit would be the potential benefits of variations in intensity, not the intensity itself.