[mad_dog01]

I have been reading alot on this forum, I have just upgraded to MH, are there any specs on type of bulbs and the PAR rating on this site, one of the moderators swears by Ushio bulbs, if they produce the best PAR rating, i can make a decision on replacing my bulbs in a year of so, I'm very happy with what i have right now but would like to get the best bulbs for my fixture when its time to replace!

[Reefland]

Try this link out:
Select from Performance Data

[acer]

I wish they had this data available for DE bulbs

[Ninong]

Originally Posted by acer

I wish they had this data available for DE bulbs

They do. Sanjay has tested both DE and SE lamps.

[Ninong]

I have used 250w 10,000K HQI DE lamps by both Ushio/BLV and AB. I prefer the appearance of the Ushio/BLV but both are nice.

According to Sanjay's latest tests:

Ushio/BLV: 103 PPFD w/o shield and 84 PPFD w/shield; 10,809 CCT w/o shield and 9,961 CCT w/shield.

AB: 128 PPFD w/o shield and 104 PPFD w/shield; 9,132 CCT w/o shield and 8,225 CCT w/shield.

That's with the standard PFO magnetic HQI ballast on both.

Note that the AB lamp tested at a higher PPFD compared to the Ushio/BLV lamp but the Ushio/BLV lamp tested higher CCT, which is why it looked nicer to me.



Notes: A shield is ALWAYS required with a DE lamp! NEVER run one without a shield! PPFD is a measurement of PAR (photosynthetically active radiation) and CCT is a measurement of apparent color. Both brands are called 10,000K and both manufacturers even claim that they are actually 13,000K. As you can see, they didn't measure 13,000K. The Ushio lamp did measure almost 10,000K with a shield and almost 11,000K without a shield. The AB lamp was closer to 9,000K without a shield and approximately 8,000K with a shield. The Ushio/BLV lamp appeared slightly more blue-white to me. My fixture came with AB lamps as original equipment but when they were ready to be replaced, I switched to Ushio (actually branded BLV) and I found the appearance more pleasing to my eye. Your mileage may vary.

P.S. -- In earlier tests conducted in 1999, Sanjay measured 128.8 PPFD and 11,723 CCT for the Ushio 250w 10,000K HQI DE lamp. Those tests were conducted without shields and using a standard magnetic HQI ballast. The brand used is not specified in the article but it was Ushio (Sanjay Joshi, pers. comm.).

[mad_dog01]

Ninong,

Maybe this is a dumb question, but in reef standard what is the optimal PAR and CCT for proper growth/lighting

[Ninong]

Originally Posted by mad_dog01

... but in reef standard what is the optimal PAR and CCT for proper growth/lighting

There is no one answer that is correct in all situations. In nature, different animals are found at different depths = different intensity of lighting and different spectrum of available light. Having said that, most animals can adapt to a fairly wide range of lighting conditions, within certain limitations. For example: you may find the identical species of Acropora growing at 1m depth and at 20m depth. Its shape will probably not be the same but it would be the same species. Its shape in shallow water would be influenced by the intensity of the available light and the turbulence of the water and its shape at 65-ft deep would be an adaptation to the available light and water flow there.

In general, most soft corals require less light than most hard corals and most SPS require more light than most LPS. Hobbyists who intend to keep a little of everything will usually choose lighting that will work with everything.

Metal halide lamps supplemented with actinic fluorescents is a favorite combination of most reefkeepers but other options are viable unless the tank is exceptionally tall. A good combination would be 6500K or 10,000K metal halides with actinic supplementation. In general, the 6500K (especially if you choose Iwasaki) will produce more PAR per watt than the 10,000K but you may find that it will also require more actinic supplementation to achieve a look that you find appealing. This is a subjective observation and it depends on what you like. The corals are quite capable of adapting to either 6500K or 10,000K.

It is possible to go with metal halide lamps of a higher Kelvin rating but just remember that these will produce less PAR per watt than the 10,000K lamps and much less PAR per watt than the 6500K lamps. They will also not have a good spectral distribution of that PAR -- it will be concentrated in the bluer end of the spectrum.

Another confusing aspect is the fact that the various lamp manufacturers play games when it comes to the advertised PAR ratings for their products. One manufacturer's 14,000K lamp might be much bluer than another manufacturer's 20,000K lamp. And all lamps will usually be slightly different in appearance depending on which ballast you select to run them on. One manufacturer even markets a 150w medium base metal halide lamp that is advertised as 50,000K. It's a very nice little lamp and would be a good choice for small tanks but it's not as blue as most 20,000K lamps.

It is impossible to cover all of the factors that come into play in choosing lighting in a few short paragraphs. I suggest you search the various online e-magazines for the many good articles on this topic. Dr. Yuri Sorokin covers this subject in excruciating detail in his excellent book, Coral Reef Ecology, but the book is now out of print and difficult to find. It's also about $90 for the paperback version and it's difficult to read because it's an English translation of the German that was a German translation of the original Russian. In other words, there are approximately 2,000 typos and phrases that sound like they came out of Donald Rumsfeld's mouth.