PAR readings in SPS tanks
 

Here's a thread that's going on over at that other big reef site about measured PAR values in SPS tanks:

http://reefcentral.com/forums/showthread.php?t=1773012

I find PAR values get over inflated when the T5 vs MH debates flare up. Above are several real world recorded PAR values over various tanks.

Here are mine with 6x24W T5s on a Sunpower fixture over a tank that's 24 x 24 x 20 with the fixture 6" above the water's surface:

At the surface: ~ 600-700
Mid tank: ~ 400
Bottom of the tank: ~ 200

20" Current USA Nova Extreme Pro, brand new bulbs (in November). Light is 4" above water's surface.

http://i290.photobucket.com/albums/l...07-07-09-1.jpg

looks to me like a lot of people need to learn how to do proper PAR readings.. if I was getting that low out of a MH system I would throw it at the manufacture.

I did notice there were a lot of electronic ballasts, which have been showen to under drive bulbs so that would explain a lot of it. Also the reason I will not buy an electronic ballast. If I were to lay out the money for a new MH set up be dammed if I would settle for a second rate output to drive it.

but at last, T5 and MH are old school, LEDs are the way to go :wink:

for the numbers though

two 250watt SE AB10K's run by Magnetic M80 ballast, 8" above the water. just under the surface was about 1200, bottom of the tank ranged between 400 to 580 at a total distance of 28"

probably way more than I needed, if you have 250 on the sand bed you should be good for anything.

My new set up will be 36 LEDs and with 40 degree optics I should be able to hit 300 to 400 on the bottom of a 17" tall tank

Steve

Go
 

some more MH PAR measurements
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WEB SHOWS

http://i27.photobucket.com/albums/c1...u/IMG_2167.jpg

- 2x Iwasaki SE 15000K on 175W electronic ballasts and Lumenmax reflectors