[Meric]

So for the last month I have been building a new hood and installing T5 lighting into it. Some quick info:

I orginally had (6) 96watt PC 50/50 lights installed over a 72X18X22 tank (4" sandbed makes it closer to 18" deep). I was keeping mostly LPS/Softies, but decided I wanted to try some SPS coral and knew I needed better lighting.

I purchased (3) ATI 11K 80W T5, (2) ATI Blue+ 80W T5, and (1) Pure Atinic 80W T5 (Made in Germany). I also purchased (6) Individual Parabolic reflectors (Which cost nearly as much as the bulbs), and the Waterproof endcaps. Since I had 96W Powercompact, I reused the Universal Triad F96HO ballasts and am overdriving the T5's to 110 Watts.

I made a few observations when setting up the system. First, If you are going to buy T5's, then buy the Parabolic reflectors (Tek). There is a significantly noticable difference in how much light goes into the tank with and without the reflector. Also the refectors clip to the bulb and can be adjusted to direct the light any direction you want. Second, overdrive those bulbs, it may reduce their life (most likely a 30% reduction), and generate more heat, but again a very noticable difference in light output.

I don't have any equipment to take measurements, but I could immediatley see a difference between (6) 96 watt PC (6 months old) and just (4) overdriven 80Watt T5's. All my red mushrooms that were growing great directly under the PC, on the bottom of the tank, started shrivelling and wither under the T5's. I had to move them into a cave to prevent them from dying. I also had to move all my Brains from the top/middle of the tank to the very bottom of the tank. Since I have added the other (2) lights, the tank is at least (3) times brighter than with PC using the same amount of wattage. Another noticable thing is Algea growth. I used to scrape my glass every 4 days, now I have to scrape it every other day, the algae grows that fast.

The only kinda of bad thing I have experienced is my Coraline algae has started to bleach a little on all the top rock, I think it will recover once it gets used to the light.

I will let you know how the SPS do under the lighting

[chevell]

You will find that even sps corals don't like too much light at all and it's very easy to have too much light in a reef tank. Don't hesitate to reduce the output by shortening the hours or by using more actinic bulbs.You will see what I mean when you start seeing what looks to be rtn in your sps's which is really just too much light.I have had these types of problems over and over again with my all VHO tank.Those stories about halides being brighter than all other types of lighting is completly wrong and very misleading.My VHO tank has 8 110 watt bulbs and i'm pushing it by having only four bulbs at a time,three of those actinics! So be careful.

[Reefland]

The only time you really need to be careful with "too much light" is if all the light causes excess heat or you are adding a new coral that came from very different lighting conditions, much less intense than where you are moving it too. In this case, the coral will require acclimation to the new light to not burn it up.

Your statement about VHO being brighter than MH is the statement that is misleading and wrong. As has been mentioned, a simple lux meter taking readings in the same tank at the same depth under VHO and then MH would easily prove your statement wrong. At this time, Metal Halide lighting is the most intense artificial lighting we can provide our corals and a true keeper of SPS and Clams would 99.5% of the time recommend them.

[Meric]

I do not think Chevell is correct. VHO may be bright, but I believe it lacks a lot of punch, better than my PC's though. True Metal Halide has a lot of PAR, but I have been reading about T5's with reflectors being as intense watt for watt as Metal halide. ie: My 600 watts of T5's put out as much PAR as (2) 250 Watt Metal Halides. Since I do not have a lux meter, I obviously cannot state it as a fact. However I can tell you that I cannot look directly at the lights on my hood, even from 7 feet away without seeing spots. I can also tell you that many areas in my tank that used to be dimmly lit or shaded with the (6) PC's are now fully and brightly lit.

I chose T5's because I would not have to buy new ballasts and would not have to get a chiller, since MH's put out so much heat, I doubt I could maintain temps without one. I have read good things about T5, and saw at least (1) reef tank that was fully loaded with SPS and Clams running on just (6) overdriven 54 Watt T5's (It was a 4 foot tank though). All SPS and Clams looked very healthy and had been in that tank for some time without any issues.