Quote:
Originally Posted by sphelps
While I applaud your skills of posting diagrams exactly how is posting diagrams of bulbs running with different ballasts relevant to bulb life? I also obtain the skills to post diagrams from articles however I will post ones more relevant to the discussion.
First we can look at the same bulb at 0 months and 17 months:
While the AVERAGE spectrum or CCT will shift in one direction the actual plot does not actually shift but rather decrease in certain areas while increasing in others resulting in a new CCT. Typically the intensity of the blue will decrease but depending on the ballast you use the other areas of the spectrum will actually increase maintaining your total PAR but changing the overall color of the bulb.
Here we can see PAR readings of the same type of bulb over time
Clearly shown is a steady par reading but a decrease in CCT
So we can pretty clearly conclude
So yes the CCT of halide bulbs will change from a result of a change in intensity of different wavelengths but this doesn't mean lower par. Results will vary for different bulbs but proper selection will prevent overly negative results.
The reason you don't see the change in CCT with LEDs is simple. The spectrum is much more defined and concentrated over a smaller area. The intensity simply decreases over time and since it lacks the other wavelengths there is no increase in other sections keeping CCT constant.
So once again the change in PAR is more directly connected to the change of intensity of each wavelength that makes up the Photosynthetically Active Radiation (PAR) and not necessarily the overall change of the Correlated Color Temperature (CCT).
Also there is more to PAR than just red and blue
http://www.advancedaquarist.com/2009/3/review
http://www.advancedaquarist.com/2008/7/aafeature1
http://www.advancedaquarist.com/2006/8/review2 |
The posting of a graph is not to show different different ballasts used but the spikes in individual ranges.
I'll agree with you that PARs values change according to the change in intensity of different wavelengths but how is that different with a shift in the spectrum? (might just be my way of reading it that i see them as the same). So would you say that the PAR value decrease is correlated to a decrease in intensity and color spectrum shift not intensity alone? now that you've mentioned that its % of intensity drop in certain spectrums.
Its true that theres more to red and blue in PAR but those are the 2 main spectrums that plants/corals utilize. There is a need for green/yellow but the 2 most utilized spetrums are red and blue thats why i only mentioned the 2.
This discussion is interesting!