calculate your light output compared to sun at sealevel

sunlight on a clear day at sealevel is equivalent of 1000w per square meter
one meter=39.5 inches
39.5/12=3.3 feet
3.3^2=10.9 feet
1000/10.9=91.7 watts per foot
1000 watts per square meter is based on incandscent.
1 watt converted to lumens for incadscent = 15 lumens

so 91.7x 15 lumens=1375.5 lumens
so for every square foot there should be 62631.1 lumens.

the effeciency of the average metal halide lamp is 65-115 lumens to watt.
specialty lights claims 80 lumens to watts for halide
and 92 lumens per watts for t5 HO

halides 1375.5/80=17.19 watts
t5 HO 1375.5/92=14.95 watts
both of these are per square foot
so to compare you tank length(feet)x width(feet)x 14.95(for t5HO) or 17.19(for halides)= x

then divide you watts you have by x

for me and the 10 gallon nano i just set up.
1.7 ftx .8 ft= 1.36 sq ft
i currently have a halide on it
so
1.36 x 17.19= 23.37 watts to emulate the sun
i have 175 halide on it raised a couple feet so lets say 100 watts
so i have 5x the power of the sun on my tank(in lumens).

if i did the calculations right and got the correct info then all i have to say is why do are lights have to be so powerful? does the sun produce alot more par per lumen then are lights?(i know the higher the kelvin the less par, and the sun is around 5,000k ).

how much of the sun do you have over your tank?


source for lumens in a square foot. http://earthobservatory.nasa.gov/Features/EnergyBalance/page2.php
note under the side column they say a square meter of sun light is equal to 19 60watt lightbulbs



edit: also i had to fix my equation as i orginally believed it was based on 100% efficency conversion of watts per lumens not the incadscent like i found stated on that site(this is the only site i found that could give me something to base the wattage on so they may just be wrong.)

also everybody please dont use this to actually set up your lighting for corals, as im sure im missing something(why our lights need to be more powerful) even if the equation is right.

 

also it would be great is someone know how much of the suns light is lost per foot or meter of water, so we can take this to the next level and find out how much sun a certain coral normally gets.

 

come on somebody do the equation,

 

I was following this and I did a 55 for example....

I have at basic (w/o Halides on) 8- 46.5" over driven T5's at 95 watts each= 760 watts

55g rough at 4'x2'x1'= 8 square feet.

760 watts x 8????

where are you getting your ftx?

 

its square feet not cubic.

so its only 4 square feet.
4x17.19=80 watts in lumens
760/80= is like 9x the lumens the sun puts out.

as you can see the is a big descrepiancy between the lighting we have found we need for good coral growth and the lumens put out by the sun

the more i look at this equation the more i think that the lumens to watts of the sun can be based on incadscent

 

1ftx4ftx14.95=59.8. 224W of HO t5/3.74x the power of the sun. I thought it was nifty.

 

But T5s you say are 90 lumens / 14.95 watts....

I'm still putting it all together... sorry... I am really good at math too and I love the work but I am trying to see what you mean.

So on a 4 square foot tank (4x14.95=59.80)

So I need 59.80 watts to replicate natural sunlight????

I have 760 on the basic side... which is 13.38 x's the suns power???

 

my math is based on the fact that 1000 watts per square meter is
equal to 91.7 watts per square foot.since there 10 square feet in a square meter.

thes watts " supposedly" based on incadescent wattage, and it takes 14.95 watts of t5 to equal 91.7 watts of incadescent. so i am basing this off of the same lumen output.

so each square foot of a t5 lite tank should have 14.95 watts over it.
so that the 14.95 x your squarefootage to get the the total number of watts over the that area. and that number is supposed to be equal to how much the sun puts out in lumens. lets call that x

so then divide your actual wattage by x and you will get how much lumens you have compared to the sun.

also everybody please dont use this to actually set up your lighting for corals, as im sure im missing something(why our lights need to be more powerful) even if the equation is right.

 

I'm a little shaky on the principles behind it, but my understanding is that Lumens and Watts aren't the best things to use to measure total energy being put out. Lux and PAR are more of an apples to apples comparison.

1 Lux = 1 Lumen per Sq M


Recommendations are no less than 3000 Lux at the deepest part of the tank. Maximum should be no more than 100,000. Natural reefs are between 110,000 and 120,000 lux at the surface and 20,000-25,000 Lux 1 meter below the surface.


Photosynthetically Active Radiation is the spectrum in which photosynthesis can occur. It's in the 400 to 700 nanometers range. Actinics and our daylights produce relatively low PAR compared with natural light. From what I've read, zooanthellic algae get more useable radiation from lower temp bulbs (6400K) rather than our higher temp bulbs. So the higher temp bulbs may penetrate further, but there seems to be an argument that the less desirable lower temp bulbs provide more of the good stuff.



Now, at 1 Watt for 15 lumens = 200 watts to get the 3000 Lux at the surface of the tank. Penetration is the key here though, at 3 feet the sunlight is at around 16% of its strength at the surface. (120,000 to 20,000, worst case). So if you had a 24 inch deep tank, that's .6 meters. Now I don't know if the loss is linear or not. If it were then maybe 50% of the light would penetrate to the base. So around 400 Watts per square meter to get the 3k Lux(ignoring wavelength).

My math sucks and it's been a long day, but depth and wavelength are important factors to consider besides just wattage and lumens.

*shrug*

 

Now that I understood!

Sorry SS, I just couldn't follow. I just finally was picking it up toward the end.