MH bulbs - 14K or 20K

[los.tejanos83]

I have 120g reef tank, 48x24x24, with a smattering of corals (primarily LPS and inverts). Which bulbs are better for coral growth while giving my tank the nice color i see in so many other well established tanks?

[joelb]

i would try phoenix 12k... they worked well for me. i usually use 20k but growth is not my primary focus, color is. the phoenix bulbs were more blue than normal 12k bulbs... in my experience.

[joelb]

ive also had lots of luck, and growth, by dosing fiji gold. it fogs up the tank during dosing but the next day everything is usually very happy. LPS and coralline grow like crazy.

[justahobby]

I believe Phoenix's bulb is 14K. I am using the Phoenix and happy with it. My opinion is a slightly blue Kelvin w/ 420nm actinic is a perfect median. It really boils down to your preference of better color vs. better growth. If you use 2 DE bulbs on your fixture, try both. You can probably find used bulbs off fellow members to see what you like best.

[JimD]

Phoenix is a 14k bulb, cant stand the thing myself, monotone with very little distinction between hues. A good 10k or maybe a 12k with actinics would be my choice.

[los.tejanos83]

Not sure what DE is/means. My MH light assy uses FC2 type bulbs.

Thanks for the tip on fiji gold.

[z28pwr]

I would go with the 14K, the 20K are just too blue.

[justahobby]

DE stands for Double Ended which is what you have vs. Mogul bulbs. Those are SE -single ended- and screw in like a house light bulb. It really didn't matter what kind you have since the bulb (Phoenix) comes in mogul form now. So forget I said the part about "if you have DE" :bigsmile:


Not sure what DE is/means. My MH light assy uses FC2 type bulbs.

Thanks for the tip on fiji gold.

[Mr Cob]

I have done all types of lighting including 10k, 12k, 14k and 20k. I'm currently running 20k and will probably never go back to any other kelvin range. For me, It's the perfect amount of blue and I do not need any supplemental lighting which is perfect since i do not run a chiller or fans. My temp range is 77 to 80.

I do run blue leds lights several hours before and after the MH for extended viewing times but not during.

[Bill S]

I have done all types of lighting including 10k, 12k, 14k and 20k. I'm currently running 20k and will probably never go back to any other kelvin range. For me, It's the perfect amount of blue and I do not need any supplemental lighting which is perfect since i do not run a chiller or fans. My temp range is 77 to 80.

I do run blue leds lights several hours before and after the MH for extended viewing times but not during.

I agree with Rob. The only thing I'd say about 20Ks is that they might not put out as much PAR, on a percentage basis, after 12 months as others do. I can't confirm that, but it just seems like they don't last quite as long.

That being said, I'm going with a 20K bulb when I get my new nano going.

[JimD]

Tried the 20k route, imo, theyre weak to begin with and get weaker as time goes on, used the XM 20k's a long time ago on a magnetic ballast, electronic ballast and hqi, they lasted about six months max, acro growth and coloration really suffered.

[los.tejanos83]

how much difference does wattage play? my recent MH bulbs were 400W 20K, i now have 250W 20K...never got any coralline growth, hoping new bulbs make a difference.

[corruption]

If the lighting is too intense, no coralline growth isn't uncommon.. The best keys for coralline is a nice stable water chemistry, high in calcium, and not-quite-overwhelming light, with a good amount of blues in the color spectrum..

-Corruption

[firecoral3msd]

I get lots of coraline with my 150w 14k MH bulbs. I also like how the bulbs make my green corals more intense green. I would go with 14k bulbs. It will look like your tank is in 15 to 20 feet of water. If you are into salt water scuba diving, you'll know what I mean.

[Mr Cob]

how much difference does wattage play? my recent MH bulbs were 400W 20K, i now have 250W 20K...never got any coralline growth, hoping new bulbs make a difference.

My entire tank is purple with 250w 20k bulbs.

[Mr Cob]

I agree with Rob. The only thing I'd say about 20Ks is that they might not put out as much PAR, on a percentage basis, after 12 months as others do. I can't confirm that, but it just seems like they don't last quite as long.

That being said, I'm going with a 20K bulb when I get my new nano going.

yeah, I'm thinking of switching bulbs out every 6 months. Jim's post above would also contribute to that decission.

I just can't get past the fact that the 20k bulbs I have now are the PERFECT lighting for me.

[txav8r]

I just can't get past the fact that the 20k bulbs I have now are the PERFECT lighting for me.


I'll second that. lol

I love the color of Robs tank. I'm going 20k when I replace my lights.

[Bill S]

Rob, which bulbs are you using?

[Mr Cob]

XM 20k single ended.

[los.tejanos83]

My 250w 20k bulbs came from eBay which may be why the blue is lackluster...since i'm a cheap skate, i may try again thru eBay but go with 250w 14k.

[corruption]

You should just shell out the price for a quality bulb -- the difference is really indescribable. You won't regret it :)

-Corruption