MH lighting 14k vs. 20K

[newbeemike]

I have a 2X250 MH sunpod with 14k MH. What is the difference between 14k and 20k. I know 20k is a bluer light. Is there any other difference. I have hard corals. and want to keep this a sps tank with a lot of acros and birdsnest.

[Bifferwine]

Corals tend to grow faster and more the lower the K rating. Most coral farmers use very low K rated bulbs, like 6K or 10K. 14K and 20K bulbs are bluer and make the colors pop more, so there's a trade off between growth and looks.

[McCrary]

Yea, some SPS keepers (me included) grow out their tanks with 10K halides and then switch to 14K or 20K bulbs to get better color out of their coral. Aquaconnect makes a 14K bulb with a PAR rating that's as high as a good 10K bulb, its the best of both worlds, but the bulbs are money.

[fatman]

I use straight 6500K on SPS grow out and frag system tanks. I use 10000K with supplemental actinic for display tanks with SPS. The higher K values are usually more pleasing for viewing but provide less lighting for growth in photo synthesis corals such as SPS. 10000K offers some better viewing when supplemented with actinic without getting to far away from the spectrum best for coral growth. The higher 14000K and 20000K are liked for viewing by quite a lot of people but the result is typically slower or possibly almost no coral growth. Most Acros with the exception of Monti's prefer the lower more intense lower K bulbs. I would suggest 10000K halides with supplemental T-5 actinic lighting. I have not yet read anything on the Aquaconnet 14000K bulbs, but I very much doubt their PAR is as good as 6500K bulbs, although it is very possible they are as good as the average cheaper 10000K bulbs.

[McCrary]

Aquaconnect makes a 14K bulb with a PAR around 400, which is what I'm getting from my Ushio 10K's. Your right about the PAR being lower than 6500k halides, but 6500K halides are yellow and although SPS grow quickly the colors are usually bland.