Any Einsteins out there?

[dlhirst]

Does anyone know if light obeys the Commutative Laws of mathematics? For example, would a light offering PAR = 300 for four hours provide the same amount of photosynthesis as a PAR=200 light running for six hours?

[Paulo]

I assume you mean in water. It is non linear with too many variables so nosimple way to caculate(might be imposible). You would have to at least increase time 3/2 time of par 300 so the estimate of 6 hours would be a good start. Some species do not reqire as much as we give them so it is possible that you could use less. Other issue is that nothing is a the same depth as everything else unless in a frag tank. In aquarium a 6 inch differance of water can have a great effect on par. Light penetration on water is non liner but can be calculated(calculus). There may be an equation to caculated the par effect on an single species' photosynthisis. Sure that is a non linear equation(more calculus). Just with these two variables, you have a very complex equation. Then you take in effect of variation of a single species(now you are at estimating). Then to throw in another wrench, you have different species and the variation withen them. Not really possible. Best is trial and error. Good luck on whatever project you are working on.

[dlhirst]

Wow, Paulo, is your last name Mandelbrot? Though he IS a fan of the seahorses, I was looking for a far simpler answer. Maybe I overstated the question...

Would the energy that hits a target coral be equivalent if it were the lesser PAR for a longer time as a greater PAR for a shorter photo period?

My example was 300 x 4. And 200 x 6

With both equalling 1200 "PAR-Hours".

I am assuming ALL other things being equal.

[Paulo]

problem is that a lower par value will not penetrate water as well as a higher par. THerefore the amount of "energy" will not be 2/3 if measured above water. would have to be measured at the target coral. Plus, if energy is not enough to stimulate growth, the energy may not be enough for coral. THere is a minimum amount(and max) of energy needed to grow coral.

[Paulo]

Also I guess I should tell you why I know some of this. I am a pharmacist and had to take many math and science classes in school. Plus have done lots of reading on lights b/c I want to do a LED build. Plus my love of reef related info is high. I am trying to provide as much info as you need to make a decision on whatever build you are doing. Biggest thing to remember it is hard to make a linear equation when it comes to electromagnetic properties(light, electricity, and radio waves). Good luck,
Paulo