The lux meter, a CHY model 332, was set to the '20k' lux setting (measuring in thousands) was placed on the table centered on the lamp. All measurements were taken under the same conditions, and measurements are in thousands of lux. For example, if the reading on the meter says 5.3, actual measured lux is 5,300."
Since the lux readings at the top of this thread show the Ushio bulb with a much greater lux reading than the Radium bulb and Sanjay's readings show that the Radium has a bit more PPFD on both the HQI and Blueline ballasts, I assume that the correlation between lux and par is less than exact in the case of these bulbs and ballasts.
Aged Salt said:Tagamet, I just changed out 2- 400W's for the new 400-10K CoralVues. I was in Premium Aquatics yesterday, & they appear brighter & more white than a 400K UShio. They had them side by side. Jeremy has not had time to lux them out yet but at $59 ea. you really can't go wrong. Of course, only time will tell on spectrum changes on the CoralVue, but I believe most will like their color rendition,Bob
Eugene Reefer said:I'm not familiar with the Harker article, but--based on one of the essays on Sanjay Joshi's website, and assuming that the lux readings here are accurate--there is not necessarily a direct correlation between lux and par. For example, in Sanjay's tests of various ballasts and bulbs the 400W Radium 20K bulb on either the Blueline electronic or PFO HQI ballast produced MORE par than the Ushio 400W 10K bulb, no matter what ballast was used for the latter. So in this case at least, more lux does not = more PAR.
Furthermore, in my experience at least very few sps turn brown under 400W Radium bulbs, and those that do likely do so for reasons other than lighting and eventually regain their original color (assuming that color was not the result of bleaching), or something very close to it.
How long a given bulb lasts on a given ballast is another issue, of course, but imo it is important not to make any blanket assertions about a particular bulb in the absence (or in the face) of verifiable testing.
George
Frick-n-Frags said:As I read through this post, the "200k" thing was confusing me.
Are there a range of settings like 200k, 20k, 2k, 200, etc on the meter???
If so the meter may be like a lot of DVM's that have what is called like a "three and a half digit" readout. You read from 0.000 to 1.999 as the range of the scale, THEN you multiply by 100 or 1000 etc (move decimal pt right x notches) to get the real value based upon the multiplier setting (range) you have selected.
I don't know why they end at 2, but maybe it has to do with the A/D conversion and some convenient binary number whatever....
Aged Salt said:Tagamet, I just changed out 2- 400W's for the new 400-10K CoralVues. I was in Premium Aquatics yesterday, & they appear brighter & more white than a 400K UShio. They had them side by side. Jeremy has not had time to lux them out yet but at $59 ea. you really can't go wrong. Of course, only time will tell on spectrum changes on the CoralVue, but I believe most will like their color rendition,Bob