Does PAR work algebraically + 40 gallon light question

LifeOfAquatics

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Hey, I was wondering if PAR worked algebraically (i think thats the right word lol). Basically, if a light says it produces 100 par at 24 inches, would that mean it produces 200 par at 12 inches, 400 at 6 inches, 800 at 3 inches, etc. Sorry if this is a dumb question I'm just looking into a new light for my soon-to-come 40 gallon mixed reef tank. I was thinking abt one viparspectra 165 light, but I saw these lights () and was thinking would it be a good idea to get like 3 of them for my 40 gallon as they'd have more coverage and would look a little cleaner. let me know what you guys think please! thank you!
 

Dkmoo

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They dont

In a vacuum they behave "inverse squareroot"ly. Meaning, for every double of distance from light source, light dims 4x.

In a tank, this formula doesn't really work bc 1) it changes medium from air to water, and 2) the internal reflection from the inside of the tank glass will bounce quite a bit of light back into the tank

Best to try to borrow a par meter then trying to guess based on math.
 
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LifeOfAquatics

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They dont

In a vacuum they behave "inverse squareroot"ly. Meaning, for every double of distance from light source, light dims 4x.

In a tank, this formula doesn't really work bc 1) it changes medium from air to water, and 2) the internal reflection from the inside of the tank glass will bounce quite a bit of light back into the tank

Best to try to borrow a par meter then trying to guess based on math.
ohhh gotcha, also, what is your opinion on buying 2-3 of these lights () than one viparspectra?
 

Dkmoo

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Lol thats a loaded question bc it depends on what kind of Par you want to achieve. "Mixed reef" is going to be a very wide range of requirements bc yiu can have softies that need less than 50par, and you can also have high end SPS that can only maintain a certain color with 400+par.

I never used kessils but maybe check out if BRS did a video spotlight on them similar to how they did for the AI primes where they talked about how many for how big for how much PAR.

Generally more spread out source is better bc it gives more even spread though of you need to achieve 400+par on parts if the tank for those acros, in such a small tank there is no way for you to also get 50 par elsewhere on the tank without creating shadow zones by getting creative with your rock scape.
 
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