jaacree

14K Vs 20K Mh All Pros And Cons

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Cody   

I have not used either but this is what i've learned about the 2 so far:

More a color difference then anything else. 20k is really blue and does add "pop" to coral coloration, 14k would be considered mostly white. Imo, it really comes down to personal choice. Some say the 14k is better for sps but the 20k is better for zoas, coloration wise. I think most people lean towards the 20k's. Keep in mind that even the same K bulbs will vary in coloration due to different manufacturers.

I'll leave the rest to people who actually run MH though.

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jaacree   

Thanks for the input I'm running 2 14ks now but they are different colors so I'm going to but 2 new ones so they will match

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I've used 10, 14, and 20K bulbs and prefer 10K with actinic T12VHO supplements. 20K MH is a dark blue and lacks the pop of the flou. VHO. Only ran the 20K for 3 months and took them off so no coral growth observations there but the 10 and 14 are the same in that regard. YMMV

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Chris   

You will see a noticeable difference in coral growth moving from 14k to 20k. Any way you could add a couple LED or T5 strips? Nothing fancy or expensive.. If possible I believe this would be a much better option.

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jaacree   

Chris I'm running two 150watt MH and two t5hos I'm just trying to get better growth so from what everyone said 14k is the best for growth

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CaptJab   

You will see a noticeable difference in coral growth moving from 14k to 20k. Any way you could add a couple LED or T5 strips? Nothing fancy or expensive.. If possible I believe this would be a much better option.

Maybe you just transposed your thoughts on this one, but the lower the Kelvin the faster the growth.

Your 20k bulbs will be more pleasing to your eyes, but the 14k or lower will give you better growth and you can add supplemental lighting to the lower K bulbs to get the look you'd like.

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Yardboy   

Thought I'd weigh in on this since after 11 years of running a metal halide tank I've tried pretty much all the different types. And to qualify my perspectie, I am now running T5 VHO's on a 200g shallow cube. I do have a 400W metal halide on the tank too, but it's only because my DIY LED malfunctioned and I've had trouble finding a component to repair it. After that the metal halide willl be gone.

It might seem containdicative that moving to a 20K will give you more growth since it seems to be a "dimmer" bulb. Fac tis that blue is a higher energy wavelength that anything else visible so while to our eyes it looks less intense, it can provide the proper energy to stimulate coral growth. Other bulbs will waste power in wavelengths of less energy and which aren't properly absorbed by the coral (google C3 and C4 photosynthesis for more info on that. Also keep in mind that corals can absorb higher wavelength light and fluoresce it at the wavelengths correct for C3 and C4 photosynthesis, so the 400K, along with the coral can produce more usable light for photosynthesis.

Now that isn't all of it. For some reason, due to the radiating metal halide mixtures inside the bulbs, those intermediate K bulbs, like 12K, 14K and 15K don't seem to always produce as much light as say a 10K. Problem with a 10K is it doesn't "look" as pleasing to our eyes, which is the second most important aspect of the light in our tanks!

Long story short, once I began using 20K bulbs, I quit using anything else. But then, getting the "right" 20K bulb and ballast combination was still hard to do! That and 20K's seem to drift into lower K ratings faster than do the other bulbs. Sigh.....It's a never ending struggle, except I feel I've got the right stuff, with T5's (overdriven to VHO's with Icecap ballasts) and LED's, and a shallow tank.

For your evening entertainment, here's the more or less definitive guide (because it's pretty much the most comprehensive) to metal halide bulb/ballast combinations. Have fun!

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