Planted Tank VIP
Join Date: Jul 2002
Location: Winston-Salem, NC
Yeah, jart, I actually learned about this stuff on that reefcentral thread. PAR is what feeds the zooaxenthellae (sp?) that provides corals with intense coloration. Some lighting configurations might appear more intense than other, while still having less PAR. Like Iwasaki 5500K bulbs. They appear brighter than Radium 20k's but have you see coral grow with one or the other? Iwasaki-grown SPS corals will generall be larger, with more drab coloration, while Radium 20k-grown SPS corals will not be as large, but have some intense coloration.
I'm really not sure how PAR affects plant growth, or maybe even plant coloration. Hobbyists are relatively new to the concept of ODNO lighting, even though it has been used in photography for decades. Time will tell what its long term effects are.
As for the output specs I gave... they are based on data from the reefcentral thread, as well as measurements taken by my Fluke AVG current meter. I measured a 4-F32T8 ballast driving two four foot tubes and current draw was approximately 0.8 amps (converted to RMS). When I took one bulb out and connected all four outputs to one bulb, current draw shot up to almost 1.7 amps! Since these electronic ballasts are extremely efficient, very little of that energy is translated to heat inside the ballast, so I generally assume most of that current draw is also seen at the bulb. But the bulb itself decreases in efficiency as current increases, evident by significant increases in heat output, so not all of that energy is translated into light.
Put more simply, even though the current draw was double for one 4x bulb over two 2x bulbs, light output isn't double because the lone 4x bulb wastes some energy through heat.
How much heat? Hmmm, I might be able to take some temperature measurements and calculate energy lost through heat convection. Must find... old college... Heat... Transfer... text.. book.
- Sam P -
plantedtanker in limbo - all tanks currently in storage