the 20KK bulbs IME give much better coloration but less growth.

regardless of the coral's light demands its always best to introduce them at
the bottom of the tank and slowly bring them up to the light.

hth
kc

"Timothy Tom" wrote in message
m...
I have been keeping SPS corals in my 150 gallon reef tank for a little
over two months since installing a 250 watt HQI minipendant with a 10K
bulb installed, using a icecap 250 Watt electonic ballast. The
distance from the middle of the bulb to the water surface is about 6
inches, with a UV shield preventing water splatters from bursting the
bulb. What I have been noticing is that the majority of my SPS corals
have either been losing their colors, or turning a fluorescent green
color. All the SPS that I have placed in the tank appear to be
healthy with good polyp extension, but once again the colors appear to
gradually fade. My nitrate and phosphate levels are zero. When I
first added SPS, I placed them high up in the tank within 10 inches of
the MH bulb, but virtually every single SPS appeared to begin to
bleach at this distance (this includes a brilliant blue A. tortusa
frag). When I noticed this bleaching, I moved the majority of frags
further down in the tank to about 16" from the bulb. This includes
the A. tortusa frag, which has made a great comeback and is now once
again a brilliant deep blue. Since I know that the A. tortusa frag is
considered one of the most light demanding species, I am guessing that
I need to move my other frags even lower in the tank. Further I am
wondering that perhaps changing my bulb to a 250W XDE 20,000K HQI may
help the coloration of the SPS. Any thoughts?