I've been playing with my new LUX meter I got on Tuesday for Christmas and have some amazing observations.
I always thought my 110 was under lit even though it has 2-175 watt MH and 2-40 watt flourescents (3.9 watts/gal)
With the sensor resting on the center cross brace, 3" below the fixture - 6,360 LUX
With the sensor 1" below the surface - 5,000 LUX
With the sensor 12" below the surface - 1,200 LUX
With the sensor 26" below the surface (resting on the gravel) - 450 LUX.
No wonder I can't grow stems in this tank!
My 29 gal Endler's tank with 1-65 watt, 6,700K CF (2.24 WPG)
fixture 15" above the sensor (off the tank) - 2,300 LUX
With sensor 15" below surface no cover - 2,100 LUX
With sensor 15" below the surface with glass cover - 2,000 LUX
Can't explain why the CF has a higher LUX reading even though it's 3" deeper, other than it's a newer bulb.
Natural sunlight through double pane window - 21,600 LUX.
Interesting to say the least.
Cheers.
Jim
New LUX meter
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DelawareJim
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Ghazanfar Ghori
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I'm not sure I'm following your comparision. To do an accurage comparison, shouldn't you measure the MH lights at 15" below the surface, and compare that number to CF measurements at 15" below surface?
Also, is it possible that your reflector on your CF reflector is more directed, where you MH is dispersing light outward circularly the further away from the fixture? (that's my idiot guess)
Also, is it possible that your reflector on your CF reflector is more directed, where you MH is dispersing light outward circularly the further away from the fixture? (that's my idiot guess)
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DelawareJim
- Posts: 1249
- Joined: Tue Dec 02, 2003 4:25 pm
- Real Name: Jim Michaels
- Location: Southeast PA
Ghazanfar; yes you're right on all those factors and I have been considering 250's for over a year. This helps justify it with the boss 
The bulbs are old, and the surface has a lot more rippling from the filter outlets vs. virtually none on the 29 gal, so that accounts for some I know.
I just kind of chuckle now when I think of my posts on APC where I argured my tank was under lit since the few stems I did try always performed better as they neared the surface if I could get them to live past the first 6" from the bottom and all the replies I got was that at 3.9 WPG I had more than enough light.
And yes Kris you're right that the MH light should have actually been measured at 15" too. But I was a bit lazy and held the sensor in the flat of my hand with the inside of my elbow resting on the rim of the tank in the 110 (about a 12" reach this way) vs. letting the sensor rest on the bottom at 15" in the 29 gal.
Jeff; I've been thinking of bring it to meetings so we can compare notes. Should be interesting when we have different fixtures on similar tanks like 29's.
Cheers.
Jim
The bulbs are old, and the surface has a lot more rippling from the filter outlets vs. virtually none on the 29 gal, so that accounts for some I know.I just kind of chuckle now when I think of my posts on APC where I argured my tank was under lit since the few stems I did try always performed better as they neared the surface if I could get them to live past the first 6" from the bottom and all the replies I got was that at 3.9 WPG I had more than enough light.
And yes Kris you're right that the MH light should have actually been measured at 15" too. But I was a bit lazy and held the sensor in the flat of my hand with the inside of my elbow resting on the rim of the tank in the 110 (about a 12" reach this way) vs. letting the sensor rest on the bottom at 15" in the 29 gal.
Jeff; I've been thinking of bring it to meetings so we can compare notes. Should be interesting when we have different fixtures on similar tanks like 29's.
Cheers.
Jim
