quick par readings

[i have crabs]

Originally Posted by fkshiu

hopefully we'll have others post their results and we can dispel (or confirm) some lighting "rules" and generate some objective numbers from which we can derive some conclusions.

this is exactly why i spent the money, i usally have 3-5 tanks and moving things from one place to another is always guesswork now i have something with numbers to tell me if its a good spot or not, also different light systems could be very close or very different from each other and having facts gets rid of some voodoo which i hate

other things i tested was a 150w coralife(just the mh bulb) brand new 10k bulb was putting out 350 at the surface and only 100 about 10"down

29g biocube with older bulbs was giving out 80-90 half way down so mabey 8" or so

[i have crabs]

well its been 2 months since i changed the bulbs in my tek light so i did some more tests,
i also tested my new cube, thier are 2x 4bulb 24" tek fixtures so 8 bulbs total same as my reef just 24" vs 48"
when i tested the reef the first time i dropped the legs to the lowest point so it would be the same always now i dont know what the heck happened maybe i had the fixture slid forward or back differently but the numbers seem better this time around, could be the clarity of the water maybe also, the spots tested might be slightly different but its just a reference so its not exact, the light on buth tanks was 4.75" off the water
on the reef tank
990-surface
525-12"
410,350 on the right- 17"
350 on the left -19"
360,290- 21"
310-26" bottom of the tank


the new cube- the water is less that perfectly clear but good still
625-surface
260-8"
240-12"
220-15"
190-21"

[digital-audiophile]

Interesting that the 48" length makes such a difference in T5's.

[i have crabs]

ya wish i knew before, when ive seen par numbers on certin bulbs it's never said a size so i figure they would all be the same or at least close,before the tank even had water in it i knew it wasnt even gonna be close

[o.c.d.]

Does the surface agitation change any of the numbers? I noticed you have a lot of surface movement on the cube with the low numbers,and the other tank looks a lot calmer. I'd wonder how the physics of light refraction really matters. I've always tried to keep my surface agitation down for this reason. Hmm Myth?

[urbanhellfire]

Originally Posted by o.c.d.

Does the surface agitation change any of the numbers? I noticed you have a lot of surface movement on the cube with the low numbers,and the other tank looks a lot calmer. I'd wonder how the physics of light refraction really matters. I've always tried to keep my surface agitation down for this reason. Hmm Myth?

Good question, I have alot of surface agitation because I like the look of the light ( MH ) and the way it "ripples" in the tank. I wonder if it does effect par?

[o.c.d.]

Wavelets on the surface act like a lens and focus the light, causing glitter lines. These beams provide a strobe effect that increases the light intensity illuminating the bottom, briefly countering the attenuation of light with depth. They have been measured as having up to twice the intensity of light on the water surface. the effect requires a point source of light, such as the sun, metal halide, or halogen lamp. Reflected up off a white sandy bottom they also illuminate the undersides of reef ledges. J. Sprung The Reef Aquarium Vol 3
Sounds like halides get another point and so would sandy white bottoms, I do miss the glitter lines from my halides. I think I'm feeling buyer remorse

[Canadian]

I think it's been reported for years that longer T5 lamps produce greater PAR numbers and are more "efficient". At least I'm pretty sure Grim or Hahnmeister posted something to that effect on RC at least a couple years ago.

[Doug]

Originally Posted by i have crabs

other things i tested was a 150w coralife(just the mh bulb) brand new 10k bulb was putting out 350 at the surface and only 100 about 10"down

Oh great. Guess I should have stuck with a 250w

[i have crabs]

the reef tank i tested with the pumps going normal, the cube i turned them down first, in the picture it looks like tons of surface movement but its mostly at the front