question about 10k vs 14 vs 15 vs 20

[jdav]

This question is relatively simple I guess, but I don't know who to ask since I am the only reefer I know personally who has MH lighting at there house......

OK so, I have one of those coralife light fixtures with the 2x150HQI mh and the 2x96w PC. Right now the MHs are 10k and the PCs are totally actinic (the stock lights). The tank seems to be really white, It almost seems like there is no blue light in the tank at all.

I really like bluer looking tanks, I basically only keep LPS with a few few SPS and like the way the blue makes all the colors look.

So my question is this, if I decide to change the MH lights in the tank, what is the difference in the ratings? I know 10k basically means the light is going to be white light and 20k has the most Blue of the MH. right? So how blue are the 20Ks? are they blue Like an actinic PC bulb, or are they blue like a 50/50 pc Bulb. I want the tank to be bluer than if I had 50/50 actinics on the tank.

Also, will there be an adverse effects to having that much blue light over corals?

Like I said, I am pretty much the only person I know who has MHs at their house so I have never really seen the difference in person. any help is greatly appreciated!

[schanz]

Looks like no one else has an opinion so I'll chime in. 10K is slightly whiter than natura sunlight which is very yellow. If you like the look of bluer tank, go 14K or 20K. That will give your LPS their best color. 20K bulbs will give the tank a "quieter" bluer look but will still appear white. They are no where near the blue of actinic bulbs. I think you'll like them. With your setup, look for some phoenix 14K DE bulbs.

[Wiskey]

The only side effect is that a tank with 20K's or 14K's will look dimmer than a tank with 10K's. The 10K's produce a higher PAR (useable light to the corals) so usally support faster groth as well.

Whiskey

[thrlride]

I agree with Schanz and Wiskey. I have the phoenix 14k's and really like the color.

With 20k bulbs you may not even need your actinics unless you want the dusk to dawn effect.

[swashbuckler]

i have yet to find any DE bulb that is VERY blue- they are all white w/ a blue tinge- no matter what 20k.. including Radiums....

kinda dissapointing b/c i saw some coralvue 14k SE's and they were more blue than anything iv seen b/f

so i guess if your looking for a real blue lamp- you gotta go SE

[moonpod]

Some of this is the eye of the beholder, some of it is bulb/ballast combos that create different colors. I have a lot of experience with 250w DE and the first thing I can tell you is that the bulbs regardless of labels break down into "yellow", "white" and "blue" IMO. These are bulbs that I've seen personally with the list going from yellower to whiter from left to right (or whiter to bluer).
Yellow--XM 10k, Helios 12.5k, AB 10k

White--Ushio 10k, Giesemann 13k and BLV 10k (near as I can tell these are the same bulb and just a tad different than the Ushio), Giesemann 14.5k (different, but not THAT different), Hammy 14k (soft white look IMO) Arcadia 14k (very similar to the Hammy)

Blue--XM 15k (but not very bright), Phoenix/Aquaconnect 14k (very reasonably bright IME), The assortment of other 14, 15 and 20k bulbs and then the Helios 20k (this one is unique IMO).

Which one YOU like, will frankly be a subjective decision.

Also FWIW, the "labels" have typically almost no bearing on the true color temp of the bulb. The XM, EVC, and Helios "10kish" bulbs run around 7k. The assortment of 14k and up bulbs for the most part are off the CCT chart (ie great than 30k in reality).

[scarletknight06]

everyone's given you good advice and I'd just like to step in and also recommend the phoenix 14k's. I just switch out my xm 20k for a phoenix 14k and (even thought its not quite burned in yet) its just a tad less blue/more white but the PAR rating is much much better. I expect it will get a little whiter when it burns in which will be perfect. If I remember correctly I read that IN GENERAL the phoenix 14k's look a little whiter on magnetic ballasts and a little more blue on electronic ones.

[swashbuckler]

^prob right, on my aquamedic magnetic ballast, the phoenix is pretty white, not much blue...