For the record, in addition to comparing LEDs and MH systems, we can also look at differing photon flux densities of various MH bulbs at different wattages to further illustrate that PAR is what counts. Sanjay Joshi has measured 400w Radiums and 250w Iwasakis numerous times in his series of articles over on Advanced Aquarist and also on the Animal Network. Initial measurements for a 400w radium are 116.2, and for the 250w Iwasaki, 116.1. Almost identical light output (at least initially, the radium drops pretty fast, whereas the Iwaski actually goes up for a few hours), yet the Radium is a much higher wattage.
http://www.animalnetwork.com/fish2/a.../2/default.asp
http://www.animalnetwork.com/fish2/a.../2/default.asp
Some interesting stuff.
08-24-2003, 10:13 PM
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