Some Lux Readings

[Ereefic]

I got my hands on a Quantum Lux Meter from a friend today, so I took some readings and thought I'd post them here. This mission was nothing professional, just me and a light meter.

The tank is a 210gal. AGA with a 6-7" DSB. Lighting is as follows.

Left and Right - 250w 10k XM on PFO Standard Magnetic Ballast in a PFO Parallel Reflector. Bottom of the bulb is 10" off the waterline. I don't know exactley how old these bulbs are, but i'm estimating them at about 14-16 months.

Center - 250w Pheonix 14k DE on PFO HQI Ballast in a PFO Mini-Pendant. Bottom of the Pendant is 6.5" off the waterline. I am estimating this bulb is 12-14 months old.

There are also 2x110w Super Actinic R bulbs that are at least 1 yr. old.

These measurement are just above the water line:

10k XM's - 430
14k Phoenix - 740

1" under the waterline:

10k XM's - 220
14k Phoenix - 460

I've added the numbers I got just above certain corals in the tank, to the photos. Hopefully they aren't to small to make out. If they are, i'll have to figure out how to make them bigger. I also took some measurements of a 175w XM 20k as well, and i'll add them in a little while.

Left Side

Center

Right Side

 

[Ereefic]

Ok, the pic thing didn't work very well. Any advice on doing that?

 

[DrBDC]

That doesn't make sense. The single ended XM 10,000K bulbs on standard magnetic ballast have a ppfd of 137 and the de phoenix 14,000k on pfo hqi ballasts are only 88. The series 2 de phonix bulbs only put out 85 with that setup. Lux is just a general measurement but it shouldn't be that different than the ppfd variation.

 

[Fiziksgeek]

Well, it might be possible. If you take into account the age of the bulb, and the reflector even more. I have a feling that the spider reflectors have a wider spread then the pendant.

Thats why Sanjays archive is so nice. Ita the same reflector and same measurement points each time.

 

[Ereefic]

Like I said, just me and a lux meter.

Under the XM's, I got a reading of 110-120 at the sandbed at the front of the tank. Under the 14k, I got a reading of 120, at the front of the tank as well.

For the 175w XM 20k (roughly 1 year old) on M57 ballast and a homemade reflector, bulb 10" off the water, I got a reading of 135 at the waterline and 1" below the water line, 80. That tank is 12" deep and has 1-2" of sand. The reading at the sandbed was about 30.

 

[want2reef]

I didn't think a reflector would make that much difference. :eek1:

 

[Scuba_Dave]

Make the numbers bigger...with an arrow
Reflectors can make a big difference

 

[Ereefic]

Ok, re-did the left side, so hopefully this works. If so, I'll re-do the center and right and post them a little later. #'s are above specific corals.

Millipora Frag - 200
Mushrooms - 105
Sandbed - 110
Rose Anemone - 180
Acro - 130
Hammer - 115

 

[Fiziksgeek]

The valuable info here is really how light penetration falls off with depth. Good info!

 

[Sullivmw]

Ereefic -

Anyway you can turn off both left and right, then take the measurements in the middle. I would be curious if the #'s are so high in the middle because of the little light spread from the left and right ?

 

[Ereefic]

<a href=showthread.php?s=&postid=7396132#post7396132 target=_blank>Originally posted</a> by Sullivmw
Ereefic -

Anyway you can turn off both left and right, then take the measurements in the middle. I would be curious if the #'s are so high in the middle because of the little light spread from the left and right ?

I returned the meter already, but will try and get it again and do as you suggested. That didn't even cross my mind when I got the meter.

At the beginning of June, I'll be swapping out the left and right MH's with Radiums on HQI ballasts, so i'll be checking those at that time.