what do you think of this fixture?

[ccCapt]

Can't you just keep half of the 20k bulbs and then replace the other half with the 6700k or 10,000k?? Then when you need to change your bulbs you can use the 20k bulbs that you took out and just replace the 10k bulbs. I think the combination of the 20k and the 10k/6700k would look nice. Actually I think it would then be your typical 50/50

If you had a 10K and a 20K, it would look pretty weird. 1/2 the tank would be whitish/yellow and the other half blue.
For those who may have never used a 5000k, 5500k or 6500k, they are YELLOW. IME, you will get the best growth AND color from these low K bulbs. If you are talking about how it looks to the eye, 14K will look better, but that is because of the light spectrum, not the color of the coral. If you turned off the lights and looked at a coral grown under 6500K, it will (or should) have better color than the coral grown under a 20K bulb. FWIW, some of the most colorful corals I've seen were grown under 10K bulbs. I'm talking actual color of the coral, not what the light makes it look like.

If you use a 67k or 10k bulb with one or two actinics will it be about the same as a 14k bulb?

Generally, 6500K (I never saw 6700K bulbs) have a much higher PAR than 14K. 10K with actinic supplementation may look similar to a 14K, but the 10K will have alot more PAR.

 

[ryshark]

I assumed that the 20k mixed with 6500k or 10,000k would like something like this
<H1>Coralife 50/50 50% Natural Daylight 6,000 K Fluorescent Bulbs

• 50% natural daylight 6,000 K, 50% actinic 03 blue fluorescent bulbs provide full-spectrum

These bulbs put out a nice color and they are half whiteish and half blue and all the colors combine.
</H1>

 

[leoslizards]

I use two 67k and one 32k on my FW planted tank. The 67k looks greenish/yellowish and the 32k looks pink. The mix of both lights looks good. I use a 10k on my FOWLR, looks white.