K ratings and PAR output on sandbed

[Hurt]

Has anyone ever taken PAR ratings on the bottom of tank with differnt bulbs? I know lower K bulbs put out a lot more PAR than higher K bulbs. I would assume a 10K would put much more PAR on the sand (20'+) than a 20K bulb would. Someone was trying to tell me a 20K bulb will put more PAR on the bottom of a tank over a 10K, and it just didn't make much sense to me. Is this the case or not? I realize the blue spectrum is the last to be filtered out, but I thought that really occured around 6 feet deep at least.

[dwdenny]

No at 10kk bulb will put out more PAR on the bottom then a 20kk bulb. As far a PAR reading under water not sure I ahve not seen any excpet for this maybe but not sure HTH http://www.cnidarianreef.com/lamps.cfm

[Entropy]

Too many variables involve do give an exact answer IMO. It would depend on the bulb, ballast, reflector, tank size, water clarity, and even bulb orientation could effect the outcome. My guess would be all things equal a 10k bulb would out par a 20k bulb, but I am running 14k bulbs (Iwasaki Aqua2) right now that are out parring (is that a word?) all the 10k bulbs in the same style/wattage. So go figure.