Lighting.....
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Thats blasting. I like blasting. More folks should blast.
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Thanks Adam and yea that's blasting alright
MY pleasure! Hmm yeah they are way stronger than that. At 6" on full intensity they are over 2000. I never even looked at it on his site actually, but Im wondering if he's referring to at the factory default setting? I mean I'd have go below 50% to get even close to 800 at 6". Who knows, I can get out a ruler and s camera if anyone really want to see it. lol My apogee was calibrated at the factory less than a years ago so I know its close enough to accurate.
That would be cool.
I've spoken to them here on r2r. Its quite a powerful set up.
IMO, 12in is a good measure. Most led I've seen take Par that distance. Most seem to need 12in to get decent enough spread to be correctly read and cover an average tank.
there actually very little in out tanks. not really enough to make a difference.
mcarroll
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Thanks again!
It's true there's a big difference between air and water, but air is not insignificant. (And it's pretty easy to figure by comparison.)
If you have a light meter, you should be able to test this yourself. It's about a 1:2 ratio.....for every additional height above the water (aka distance from the light source), intensity drops by about half. So if you're getting 1000 PAR at 6" and you raise the lights up to 12", you should see about 500 PAR.
In water, it's more like 1:4. If your water is pretty crystal clear, then you may get somewhat less attenuation and if your water is more full of plankton, microbubbles and gelbstoff you might get even a little more attenuation.
I would, however, bet that's based on the spread of sunlight, which is generally really spread/scattered/etc. (A high percentage of photons present are on on a reflective path....they will not enter the water.)
We have a tendency to use reflectors and lenses to defeat these spread/scattering effects....and I've read that collimated/concentrated light does behave differently. (A lower percentage of the photons present are on a reflective trajectory. More will enter the water.)
But most tanks should be about the same since most reflectors are pretty similar and most folks seem to use 90º or 120º lenses....just look at a few PAR maps side by side while accounting for these differences and you should be ableo to see the average.
(It's all an expression of the Lambert-Beer Law. Which in a nutshell explains that attenuation is proportional to path length + attenuation is proportional to concentration of material the light is passing through. Anyone know of a website/post/something that explains the science of this in plain english though? I've found at least some of the journal articles about it but they're indigestible at my level. Too many formulas.)
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The intensity (or illuminance or irradiance) of light or other linear waves radiating from a point source (energy per unit of area perpendicular to the source) is inversely proportional to the square of the distance from the source; so an object (of the same size) twice as far away, receives only one-quarter the energy (in the same time period).
It’s the square inverse law. Twice the distance 1/4 the intensity.
Thus i run my radions on 100% 18 over the tank. Better spread same par as turning them down.
It’s the square inverse law. Twice the distance 1/4 the intensity.
Thus i run my radions on 100% 18 over the tank. Better spread same par as turning them down.
Outstanding! Thanks for the post. I have been saying the Adam's dumbed down version of this exact concept for years. I never understood running a fixture 5 inches off water, at 30%. Made absolutely no sense to me at all.
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I'll drink to this! *cheers*
It's only when you say it folks belive it.
What do I know, I've just been putting lights I've stuff for 30 years.
Lol.
As Sargent Shultz used to say I know nothing lol
mcarroll
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Followed you on this one. Nicely posted!
Of course there's no free lunch. Running lights high carries performance costs too – just different performance costs than running them low.
Also, "spread" is a concept that needs more development. You do not automatically get better spread from raising lights. It depends on the specifics of the situation. Also, I believe LED's do "automatically" wear faster at full-output.
(I like 30º lenses and pretty high mounting points for my lights too, BTW....speaking as a fan.
)I agree on the wear and tear for sure. Not to mention the over all cost of operating the light at full intensity . There is a definite difference between the rational of a home hobbyist and full blown mariculture operation as well. So , as far as spread goes it basically having to run less units / bulbs (depending on fixture) where as the upfront cost to a home hobbyist is really the only concern for most. I know I’ve always done it this way as not enough light is easier to fix than not enough? I hope that makes sense. Kinda old school way of thinking about it but we used to acclimate corals to metal halide by raising the light up and slowly lowering it down. I feel this is more efficient than setting a dial , or intensity setting as usually 80% of max is not the same output as the actual 80% measurement of the intensity at 100%. I hope I’m explaining my logic correctly here. Lol.
Thank you for the follow. I enjoy a lot of your posts as they are very informative. Returned in kind.
Thank you for the follow. I enjoy a lot of your posts as they are very informative. Returned in kind.
That was actually the post that led to the post about the square inverse law. Lol. It needed to be clarified that there was no arguing with your logic as it a law of physics that applies everywhere. Even when making grits in Vinni’s kitchen .Not sure about radiation intensity though. I may have left that lecture to go hit on girls in college . Ill look it up.
Edit: radiation applies the same regardless of lensing. Applies to lasers as well. Physics is magic i swear.
Edit: radiation applies the same regardless of lensing. Applies to lasers as well. Physics is magic i swear.
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You actually do generally.
A point source (narrow flashlight Kessil ) farther and farther from a subject naturally gets wider increasing the spread.
Think apple , or in lighting class, a grey ball. The point is only on the center of the ball. Raise it and the spread covers the ball. Then the surface the ball is resting on.
Keep the intensity on the original spot the same.
The under side of the ball will be dark initially.
As the light gets higher and higher the spread increases naturally and the dark side of the ball gets more and more light. Increasing coverage.
The lightning of the dark side is due to the increase in ambient lighting. The amount of light now bouncing off of more and more surfaces.
If the ball is now in a box or cube , the best spread and accidental coverage is archived by placing the spread so it encompasses the top of the cube so it bounces off the walls of the cube and the surface the ball is sitting on.
So if you have a single kessil aim for the top of the cube , not the bottom where the coral is.
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