250 watt SE MH lamps compared
- Thread starter gregt
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SHOmuchFUN
New member
For decent growth you'd want PAR to be at LEAST 300. I'd say around 400 for optimum growth.
I too was thinking of trying the 15ks, but with upgrading to a larger tank and all the added real estate I have, there's no way I'm switching to a bulb that has a lower par rating than a 20k or radium. That's crazy.
I too was thinking of trying the 15ks, but with upgrading to a larger tank and all the added real estate I have, there's no way I'm switching to a bulb that has a lower par rating than a 20k or radium. That's crazy.
SHOmuchFUN
New member
I'm not saying you won't get ANY growth, but it'll be slower than bulbs with a PAR of around 300.
conspicman
New member
If you would like to get great info on lighting/par/spectural output. Go to reefs.org and look up sonjays reef homepage and he has all the comparisons you could ever want. He has done extensive research on all of the major brands. The information he has will really open your eyes to the reality of aquarium lighting. If your not interested in going through all of the research than I will tell you what his determinations are, the best over all lighting (lumens,par and cost of operation) are single or double ended (there is no diffrence contrarey to popular belief) 250 watt 6500 K. They produce almost as much light as the 400 and are cheeper to operate. The 65K's are the closest to natural sun light and they last up to 2 yrs woth less than 10% reduction in par. By far this set up is the best way to go. I recentlly went to a lecture he held, and his research is very extensive and complete. Hope the info helps.
MiddletonMark
Premium Member
aiber said:
Hi Albert ... what are you growing?
IMO, 300 might be what a few corals desire, but I've found a wide range of light-intensity-demand from my corals. Even among my Acropora, some fade under the most light, some brown under weak light - even among them there seems to be a range of tolerances, and of desired light.
For lighting info, check these articles:
http://www.advancedaquarist.com/issues/feb2002/Feature.htm
http://www.advancedaquarist.com/issues/august2003/feature.htm
Maybe not exactly what you're looking for, but more information. Hope it helps.
RedEyeReef
Active member
SHOmuchFUN
New member
I was curious about the HELIOS 20ks. Any info on them?
RustySnail
New member
I have a question/comment regarding PAR readings and various lamp types. In any of the rated PAR values on the 250W SE Comparison have adjustments made to account for the Extreme Non-Linearity of the measurement device?? If you look at the product spec's page for this device it shows a rather exponential drop-off on the blue end of the spectrum; which is the range of most concern for photosynthesis. At 400nm, the meter only reports 30% of the actual intensity. If you just compare the PAR for a 10k to PAR for a 20k without correction for the meter's non-linearity; the results will vastly favor a 10k lamp. If this correction was not made in the posted results; IMHO the results are likely skewed to a large extent.
JB-NY (and RC)- Dont get me wrong; it's a GREAT thread and very nice work on the topic of MH lighting types. If there is a 'fudge factor' that can be applied to get more accurate results; all the better!
JB-NY (and RC)- Dont get me wrong; it's a GREAT thread and very nice work on the topic of MH lighting types. If there is a 'fudge factor' that can be applied to get more accurate results; all the better!
RustySnail
New member
DP 
RustySnail
New member
...
JB NY
Active member
RustySnail said:
But of course!
I was able to get hold of two Li-Cor sensors and compare the results with that of the apogee sensor. The differences are on my web page as well as buried someplace in this thread. Differences on average were about 3% the highest I think around 6 or 7%. More than good for hobbyists.
Also the initial batch of lamps that were tested were all sent to Sanjay so that we could confirm our readings with each other. In almost all cases the reading he and I got were almost the same.
RustySnail
New member
I read this on your webpage; but that's not the issue. Both the Li-Cor and the Apogee have a non-linear response across the light spectrum. The fact that the results of the Apogee are in close agreement with the Li-Cor shows that the sensors are similar in their response to the different wavelengths; but both sensors respond much less to blue light than they do to yellow. The Apogee sensor loses 100% response before 700nm in addition; but we are not as concerned with the red spectrum as the blue.
My question is more fundamental than if one light meter reading agrees with another. What I am trying to get at is that if the sensor is not recording blue light at the same level that it would green, then it's reporting less PAR on a lamp that is skewed toward the blue. This makes it difficult (if not impossible) to compare lamps that are of different spectrum profile because the output of the sensor will differ greatly depending on the color temp of the light produced (even if it is the exact same intensity).
The Apogee product spec sheet covers this issue; but then whitewashes it with the statement "Fortunately, common light sources are mixtures of colors and the spectral errors offset eachother". It goes further to state "The sensor measures green light (500-550nm) accurately, so it can be used to measure the radiation inside and at the bottom of plant canopies." Niether of these statements apply to the situation of lamp comparison; it is not that simple if you are trying to make direct PAR comparisons between different spectrum lamps.
IMHO there is a possibility that the blue spectrum lamps have much higher PAR than you and Sanjay are reporting; it could be that all of the lamps have a mean luminoscity that is somewhere around 500 PAR (white lamps recorded 'high' blue lamps recorded 'low'). Of course, I could be wrong; is Sanjay using a similar method of light measurement?
My question is more fundamental than if one light meter reading agrees with another. What I am trying to get at is that if the sensor is not recording blue light at the same level that it would green, then it's reporting less PAR on a lamp that is skewed toward the blue. This makes it difficult (if not impossible) to compare lamps that are of different spectrum profile because the output of the sensor will differ greatly depending on the color temp of the light produced (even if it is the exact same intensity).
The Apogee product spec sheet covers this issue; but then whitewashes it with the statement "Fortunately, common light sources are mixtures of colors and the spectral errors offset eachother". It goes further to state "The sensor measures green light (500-550nm) accurately, so it can be used to measure the radiation inside and at the bottom of plant canopies." Niether of these statements apply to the situation of lamp comparison; it is not that simple if you are trying to make direct PAR comparisons between different spectrum lamps.
IMHO there is a possibility that the blue spectrum lamps have much higher PAR than you and Sanjay are reporting; it could be that all of the lamps have a mean luminoscity that is somewhere around 500 PAR (white lamps recorded 'high' blue lamps recorded 'low'). Of course, I could be wrong; is Sanjay using a similar method of light measurement?
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