20k not blue enough

bv_reefer · #1 03-11-2008, 11:38 PM

i'm running a 20k 400-watt XM bulb over my tank, and i'm still not getting the ''deep blue'' i was hoping for at all, everything around the tank is blue

but not the tank so much, i guess you could say it's kind of in between 10k and 14k really. it's about 10'' or so from the water surface and the reflector is kinda crappy, could this be the reason? i was really hoping for a deep reef kind of blue..

midgetwaiter · #2 03-12-2008, 04:45 AM

Try another ballast, electronic ones will give you the most blue colour but it can vary a lot with 2 different magnetics as well.

bv_reefer · #3 03-12-2008, 06:47 AM

think it's the ballast? the ballast is made for that type of bulb and is running it pretty nice, quiet when on, and bright as heck, i'm just wondering how to get all that blueness directed to my tank, real wierd when you walk in the room everything is blue around you from the bulb yet the actual tank has only a blue tint..

wickedfrags · #4 03-12-2008, 11:26 AM

Yup - it's the ballast. The ballast I have runs 20K XM's very white, even with actinic supplements. Most people think my tank has 12-14K lighting when they see it. I also think Starphire glass makes a tank look more white than blue.

Whatigot · #5 03-12-2008, 02:00 PM

I know my Coralife 150 hqi 20ks are really white.
I just bought them used though so maybe thats why they are so white?
in any case, I'm going to grab some pheonix 14k's or the aquamedic 14ks as those seem to be the bluest I've seen with my own eyes on an electronic ballast.

bv_reefer · #6 03-13-2008, 07:36 PM

ok so i changed the reflector to a new polished one and dropped the fixture an inch closer to the surface and it's quite blue now i guess it was the crappy reflector i had, could it be that it takes a few days for the bulb to break in?? reason i'm asking is that the bulb seems much more blue than when i first put it in it was pretty 10k'ish,

Whatigot · #7 03-13-2008, 07:44 PM

halides do go through a "break in" period and the spectrum/color could change throughout that process I suppose.

Moving it closer with a shinier reflector couldnt've hurt either though.

fkshiu · #8 03-13-2008, 08:00 PM

Relatively speaking, XM 20Ks are pretty white for a "20K" bulb regardless. Not surprising since I think their 20K has higher PPFD than their 15K bulb. The best "deep blue" from a "20k" bulb that I've ever seen is still the Radium 20K.

Stones · #9 03-13-2008, 11:08 PM

Most metal halide bulbs take approximately 100 hours of use before they are considered to be "broken in" and show their true colour output.

I've used many different brands of 20K bulb on my reef over the years and all of them looked closer to 14K than 20K bulbs I had seen running on other tanks. In my case, it was my ballast (PFO HQI) causing the bulbs to look whiter. When I switched to the radium 20Ks which were meant to be run on a HQI ballast, colour improved somewhat (still looks to be between 14K - 20K) and my growth rate also picked up.

bv_reefer · #10 03-14-2008, 12:35 AM

100 hours eh, i notice everyday it's getting bluer. ya fkshiu i wanted to go with radiums badly, but i'm using an m59 ballast ment for probe only lamps, so radium was out of the question, the reflector definitely picked up the stray light, so looks to me that it's brighter, either way i'm already getting wicked growth from all the corals so definitely no complaints, like my gsp's that were'nt coming out for weeks on end when i wa running my old hqi's. anyways thanx for the responses..