[StirCrazy]

Originally Posted by Myka

I have been leaning away from PAR lately...you can get great results without lighting the crap out of the tank. My LPS are all on the sand or the outskirts of the lights (my fixture is designed for a 36" tank and mine is 48" so the halides don't reach the ends very well...perfect for the LPS). They are all well colored. I changed the bulbs to cheap 20K to lower the Kelvin too.

you have to watch that, higher K bulbs don't produce less PAR, but rather PAR that is misread and reported as lower. PAR sensors over report PAR in lower K, IE the 6500K bulbs and way under report the amount of PAR in 20K bulbs. this has to do with the calibration to give you an average PAR level over a wide spectrum.. so by making it report properly under day light when we measure bulbs that have huge spikes of 380 to 420 nm it throws the average off as it isn't calibrated for that range specificly. so because of the nature of blue/violet light it can't read it properly and under reports it. the opposit is tru if you had a huge spike of green, the wave length of green overpowers the sensor and makes it think there is more PAR than there actualy is.

a practical example of this is about 6-8 years ago when everyone was running iwasakies and Ushios, then changed to the new radiums.. the radiums were listed as about 10% less par then the Iwasakis and about the same as the ushios, but people were bleaching corals left and right.

Steve