250 WATT Metal Halide

[LoneStar]

If you are running a 250 watt MH light with a 10k bulb, do you need to have a blue actinic light for a reef tank??

[Reef69]

Thing about 10ks is that they lack of blue..IMO...i'd go with 14k's

[Polkster13]

Depends on if you want growth or color. 10K tends to make the corals grow faster while 20K makes the corals "look" good. 14K lamps are a good compromise between the two.

[GaryP]

10Ks laclk blue? That's news to me. Check the spectrum out on the XM Mogul bulbs that I am using.

http://www.xmlighting.com/images/250w10kspectrumMogul.jpg

[jaded]

it definately depends on the bulb and ballast!!!

check this out to compare lights side by side (http://metricksystem.com/chris/250wcolour/)

[GaryP]

Check out the comparison on the PAR value. That should tell you a lot. The 20K bulbs have 40% of the PAR value of the 10K. That kills your growth. You are burning up a lot of electricity for not a lot of light.

[z28pwr]

It's also a personal prefernce. Most people see the best growth with 6500K Iwasaki bulbs, but yet they look very yellow and not very appealing to the eye.

It just depends on what you want to keep, how fast you want it to grow and what colors are more appealing to you. I personally like a nice blue hint to everything, thus I like the 20K XM buls, even though they don't have the same growth rate that the 10K's have. You can always run 10K bulbs with some atinic VHO's as supplement.

[GaryP]

You can always run 10K bulbs with some atinic VHO's as supplement.

That's what most people I know are doing in larger tanks. You have a lot fewer options with a smaller tank simply because you don't have as much room.

[Reef69]

I dont know, i tried a 10k bulb on my 250's and it looked ugly yellow..

[GaryP]

It depends on what 10K you used. No two are goinig to have the same spectrum, and what do you mean by ugly yellow? Compared to what? A 20K? Yes, a white light is going to look yellow compared to a blue bulb. I can hardly tell when my actinics are off with my 10Ks.

It comes back to what I said earlier, no single bulb will do everything you want it to do. Its a physically impossibility.

[JimD]

The ONLY, and Ive seen a lot, 10k bulb Ive ever seen that didnt need any actinic supplimentation, was the Geissman 10k DE Marine bulb I guess its considered a Megachrome, run on a magnetic ballast, these bulbs look incredible!

[GaryP]

Jim,

I believe the bulb you are referring to is a 13K. Spank me if I'm wrong.

[JimD]

I just checked and you sir are semi correct, they offer three diferent flavors, "Marine"-12.5k, "Coral"-14.5k and "Blue"-20k. The "Marine" will run slightly bluer on an electronic ballast. In my opinion, one of the most impressive DE bulbs Ive seen. No spanking for you!

[Tim Marvin]

I ran the 14.5k for about 8 months and switched to coralvue this time. I am very impressed with the 10k coralvues and t-5 actinic.

[JimD]

How do the 10k CV's look without actinics after burn in?

[Tim Marvin]

Crisp white.

[JimD]

CV electronic ballast?

[Tim Marvin]

Yes, the HQI/PFO Pulse start ballast fired them a tiny bit yellow, but it could have been I just didn't wait long enough for them to burn in. They take about 2-3 weeks to really burn in.

[GaryP]

The Geisman is in fact 12.5K but is commonly referred to as a 13K.

[aquadoc]

I use the mixture of both 10k and 14k both Coralvue, plus actinics.
That way I can have growth and color.
I used to run nothing but 20k, but wasn't happy with the growth, espeacialy the SPS.
Now that I have switched they have colored up the most, and started to grow in a furry.

[GaryP]

Is there an old vs. new Iwasaki bulb?

I ran them when I first bought my 125. It came with them. I had huge growth and I didn't really know the difference on color until you guys polluted my mind. I went to 14K and loved the color, but my growth grew to a halt. Now I have gone back to the middle with the XM 10K bulbs.