I saw 10,000K MH lamps in Israel used as colored blue lamps, or as a general purpose daylight MH lamps in floodlights. I think they were simply blue MH lamps that was overdosed with Indium to get the color, which was bluish white.
Most of the "10,000K" MH lamps i saw was probably simply low cost chinese blue MH lamps that overdosed with indium iodide, since i encountered this phenomenon also in green MH lamps (Pastel greenish white or yellowish green color).
In aquariums, we uses usually linear plant growing (With magesium fluoro germanate for narrow band red and barium aluminate for wide band low intensity blue) T8 fluorescent lamps, and sometimes even as simple as daylight halophosphors 765 T8 fluorescent lamps.
Most of the "10,000K" MH lamps i saw was probably simply low cost chinese blue MH lamps that overdosed with indium iodide, since i encountered this phenomenon also in green MH lamps (Pastel greenish white or yellowish green color).
In aquariums, we uses usually linear plant growing (With magesium fluoro germanate for narrow band red and barium aluminate for wide band low intensity blue) T8 fluorescent lamps, and sometimes even as simple as daylight halophosphors 765 T8 fluorescent lamps.
Thanks it Looks a Greyish Blue like a overcast sky
All the Best
Colin