First, YES, I know with the different bulbs we are not comparing apples to apples... however, the numbers are so massively different that we are comparing apples to hay balers.
Background: My frag tank (housing Rob's corals, mostly) had T5s, 4x24w HO to be exact, on it. The corals were showing signs of light deprivation (browning, etc) so we decided to test it, and the numbers were so bad (even with new bulbs AND ballasts... 150 PAR at the surface) that we decided to throw a 250w MH up there and get these things back where they should be.
The frag tank is 18x24x12. The T5s were right on the rim; the MH was installed so that the bulb was 6" from the surface, 12" from the frag rack and 16" from the bottom. For the math-impaired, that means the water is 10" deep and the frag rack is 4" off the bottom.
)
Sooooo, we installed a Lumen-something (I can't keep them straight) reflector, and an IceCap 250w ballast. We brought from his house three bulbs... an IceCap 10KK (nearly new), an XM 20KK (old, but exact unkown) and a "Reef Grow" 15KK, same as the XM.
The results from the three bulbs was eye-opening. Yes, I know the lower K bulbs make more PAR as a rule... but the age obviously made a HUGE difference.
Bulb one:
IceCap 10KK: Surface 700, frag rack 600, bottom 300.
Bulb two:
XM 20KK: Surface 350, frag rack 180, bottom 70
Bulb three:
Reef Grow 15KK: Surface 300, further testing abandoned.
So, I realize that the bulbs were all different, but the PAR numbers are so different that I'd have to blame it 90% on age, since we were unable to test a new/old bulb of the same brand for a control.
I only post this as a kind of public service... I had always been told that old bulbs experience "spectrum shift", but I've never read or been told that they lose massive amounts of PAR production.
Am I off base in my conclusion from this? Am I right that it seems to be far more age than brand/temp that contributes to this? I mean, if a 10K really produced twice the PAR of a 20K, we'd all be enjoying our yellowish light and brownish corals, right?
Background: My frag tank (housing Rob's corals, mostly) had T5s, 4x24w HO to be exact, on it. The corals were showing signs of light deprivation (browning, etc) so we decided to test it, and the numbers were so bad (even with new bulbs AND ballasts... 150 PAR at the surface) that we decided to throw a 250w MH up there and get these things back where they should be.
The frag tank is 18x24x12. The T5s were right on the rim; the MH was installed so that the bulb was 6" from the surface, 12" from the frag rack and 16" from the bottom. For the math-impaired, that means the water is 10" deep and the frag rack is 4" off the bottom.
)Sooooo, we installed a Lumen-something (I can't keep them straight) reflector, and an IceCap 250w ballast. We brought from his house three bulbs... an IceCap 10KK (nearly new), an XM 20KK (old, but exact unkown) and a "Reef Grow" 15KK, same as the XM.
The results from the three bulbs was eye-opening. Yes, I know the lower K bulbs make more PAR as a rule... but the age obviously made a HUGE difference.
Bulb one:
IceCap 10KK: Surface 700, frag rack 600, bottom 300.
Bulb two:
XM 20KK: Surface 350, frag rack 180, bottom 70
Bulb three:
Reef Grow 15KK: Surface 300, further testing abandoned.
So, I realize that the bulbs were all different, but the PAR numbers are so different that I'd have to blame it 90% on age, since we were unable to test a new/old bulb of the same brand for a control.
I only post this as a kind of public service... I had always been told that old bulbs experience "spectrum shift", but I've never read or been told that they lose massive amounts of PAR production.
Am I off base in my conclusion from this? Am I right that it seems to be far more age than brand/temp that contributes to this? I mean, if a 10K really produced twice the PAR of a 20K, we'd all be enjoying our yellowish light and brownish corals, right?
