Method/tool to find PPF?...Please help

[bta]

Hi,

I need a method to find the ppf of HID light (MH and HPS). I would like to find a relatively inexpensive quantum meter that is accurate in PAR range, a layman's mathematical solution, etc.

I was going to buy the basic Apogee quantum meter ($170.00) but it doesn't measure 650-700nm range and weights blue too heavy. it also has a 3% margin of error and only measures up to 1,999 µmol which is not high enough. Then I found the LI-COR meter, it's perfect but I think it's over $1,000 and I can not afford that.

Any solutions, or would someone ike to loan me their spectroradiometer

[bta]

Ok, I guess the mathematical solution is out, or am I incorrect?:

(from http://reefs.org/phpBB2/viewtopic.php?t ... light=ppfd)

Code: Select all

Quote:
Since it is nearly impossible to find the Photosynthetic Photon Flux Density ratings of the bulbs can we simply use lumen/Watt ratings of the bulbs for having a general idea of light intensity of the bulbs? Is there any conversion formula for lumen/Watt to PPFD or any source showing the light intensity of different depths of tropical seas?

In order to convert, you need to know the precise spectrum. If it is daylight, driven by Sun, about 40 lumens corresponds to 1 PAR. But it would be reckless to apply this to halide lamps.