These PAR measurements were taken in "open air". Based on my experience, they will differ little when measured with water in the tank. The fact that these lights use surface mounted emitters without any optics might provide different results through water - I'll remeasure once the tank is wet.
Has anyone ever tested the par of a compact fluorescent light bulb like in a room light? I was thinking about changing over to those to possibly save some mula on the electric bill but keep all my plants alive. Currently have 160 watts... IK watts, that was what I was told I needed when I started my tank 6 weeks ago, over my 72 bow (4xT12 6500k). I saw something on youtube about this kid who used Compact Fluorescent light bulbs over his tank and had some good results over the two weeks. Is that a bad idea to change over and does the watts mater on those at all for PAR readings?
I saw some of those in a store - there's a Lumens spec on the box, which contains one "bulb" & the fixture. I think the 24" version is rated at 400 lumens, so if you (generously) triple that, by adding a couple more "bulbs" at ~$27 ea., you'd be right there with the Marineland single brights as far as growing plants would be concerned (not enough light).