This isn't true. If you cool a T5 lamp too much you drastically drop the output. Therefore attempting to add active cooling to a lower end T5 fixture is more complex than just blowing air over the lamps. Some lamps have cold spots at one end of the lamp and others don't - this changes the position where the air flow should be directed. The optimal operating temperature is somewhere around 115F (45 degrees C - see this reference: http://www.lighting.com/content.cfm?id=2071&page=/). Above or below that and you see degradation in lamp output and changes in ballast wattage draw --> poorer efficiency.

The biggest problem with respect to gaining even greater wide spread use of T5 lamps in reefkeeping is the general ignorance regarding output and optimizing color and PAR by changing numerous variables (reflector design, lamp choice, ballast choice, active cooling, etc.). MH tends to be the default because it has been around a long time (with good reason) and its application is fairly well understood. In North America we still don't have a good handle on what constitutes an ideal setup (hence seeing Sunlight Supply Tek lights being recommended over and over again despite their poor reflector design and lack of active cooling). And then there's that shimmer issue . . .

I will be there tomorrow. can post some numbers comparing a MH set-up and a T5 set up. lol jdigitals 2x250watt vs my 6x54watt t5HO. thats if its ok with him...

Can't wait to see the results.:lol:

K talked to him. shall get some numbers tomorrow. only difference is his tank is 20" tall and mine is 16" i believe.

When i was refering to cooler bulbs i was mostly thing of using a fan to blow across the bulbs. But like i have mentioned before, cheaper fixtures (TEK, NEP) can produce great results. Sure the ATI is an amazing fixture but for me, a bit out of my price range and for your average reefer they don't want to spend more than $500-700 on a fixture. Its not just the fact that I am running a TEK but alot of people look down on them.

I think the TEK is great, I had way more issues with heat from MH lights. (I have a nice burn scar to prove it)

I see a lot of set ups where people add a bank of fans to their TEKs perhaps something I will try down the road.

K guys so here are some numbers from my T5HO TEK (bulbs are 10,000k; fiji purple; 10,000k; fiji purple; 10,000k; reef blue. all bulbs are aqua science. I measured first at my sand bed, than top of the rocks (which is mid tank) than surface reading. Measure used was a milwaukee smark luxmeter sm700 on the 20000/50000 x 100lux setting. Tank is 16" deep and the light is 3-4 inches away from the surface.

http://i37.photobucket.com/albums/e6...IMG_0010-4.jpg
http://i37.photobucket.com/albums/e6...IMG_0011-3.jpg
http://i37.photobucket.com/albums/e6...IMG_0012-4.jpg
http://i37.photobucket.com/albums/e6...IMG_0009-3.jpg
http://i37.photobucket.com/albums/e6...IMG_0008-2.jpg
http://i37.photobucket.com/albums/e6...IMG_0007-6.jpg
http://i37.photobucket.com/albums/e6...IMG_0004-5.jpg
http://i37.photobucket.com/albums/e6...IMG_0003-4.jpg
http://i37.photobucket.com/albums/e6...IMG_0001-3.jpg



Also for fun, my 20" NEP using stock current bulbs (3 10,000k; 3 aticnic's). One reading at surface and the other is the sand bed.

http://i37.photobucket.com/albums/e6...IMG_0014-2.jpg

http://i37.photobucket.com/albums/e6...IMG_0015-3.jpg

K so now comparing against 2x250watt MH using luxmax 3 with 14,000k ushio bulbs. I didn't go all the way down but this is just to show. still started at surface reading, than about 8 inches down, than 16 inches down... about. Same settings and both tanks have had the lights on for over an hour and a half.

Surface readings

http://i37.photobucket.com/albums/e6...IMG_0002-5.jpg
http://i37.photobucket.com/albums/e6...IMG_0003-5.jpg

8 inches down readings

http://i37.photobucket.com/albums/e6...IMG_0005-6.jpg
http://i37.photobucket.com/albums/e6...IMG_0006-5.jpg
http://i37.photobucket.com/albums/e6...IMG_0007-7.jpg

16 inches down readings

http://i37.photobucket.com/albums/e6...IMG_0008-3.jpg
http://i37.photobucket.com/albums/e6...IMG_0009-4.jpg
http://i37.photobucket.com/albums/e6...IMG_0010-5.jpg

Now the whole point to me doing this test was not to compare which was better but everyone knows that a good 250watt MH set up will be able to grow SPS easily. Now this shows that a good T5 set up does compare to it with close numbers. Sadly i wish t5's had the shimmer

The end result is that both MH and T5 are great and are equal options for reefers. Some major differences between the two are heat output, color options, price of unit/bulbs, and power usage. Depending on the options that are more important to you, will decide which route to go

How close to the glass was the meter? We found that the light reflects off of the glass and hence the center of the tank lower down actually had a lower reading when we tested a while back.

those lower tests were done about 1/3 the width of the tank for the lower tests

I can see what your talking about though