Dual Actinic (460nm & 420nm) bulb question

Sorry for the dumb question. I just got a new light source that has 2 Dual Actinic (460nm & 420nm) bulbs. For both of the bulbs it appears that only one side is on when turned on. When I flip them around, the illuminated side is the same, so it seems to be more of a bulb issue than a fixture issue, but then, both bulbs are the same.

Is this just because one of the wavelengths of the actinic bulb is much brighter than the other, and thus, it only looks like one side is on? Is that how the dual bulbs work? One wavelength on one side and one on the other?

TIA - sorry for the ignorant question.

 

Can you take a picture of it? The only difference you will see is that one will look slightly more purple in color than the other. Is your bulb CF?

 

I'm at work now, so can post a picture after I get home this evening.

Does CF mean compact fluorescent? I'm not completely sure (sorry I'm new to this stuff, coming from basic freshwater stuff). The bulb is the Dual Actinic 420/460nm SunPaq Powercompact. I don't know if 'powercompact' is the same as CF or not...

 

Yup, those would be power compact flourescents. How those bulbs work are strange. If one half doesn't work, the entire bulbe won't work. If one side is lighting up, it's safe to say both are lighting up. Dual Actinics tend to blend into each other, since their spectrum is fairly close. It's easier to see the color differential when they are separate bulbs. The wattage for each side will be equal, though one will look brighter due to different PAR and lumen values for each wavelength.
What animals/fish are you planning on having in your tank?

 

I've always been a big fan of brackish fish in my freshwater forays (I've been doing it for over 15 years), so I thought I'd be ambitious and try a slow acclimation of some brackish to salt water. When I get to full salt I'll probably just go with fish and live rock, but will see how it goes before jumping to any corals...
I just inherited a 120 gallon tank and thought it might be a good time to try...

 

One side of the dual bulbs looks like it is not working that's the way it's suppose to be.. i have the same bulbs. However you should be able to seem some sort of illumination. It shouldn't be completely dead. A very faint purple is normal... also give it a few minutes to warm up it takes it 5-10 minutes to really crank up.

 

Also these are my favorite actinic bulbs.. they really make fluorescent things glow. My favorite LFS uses them in his displays for that reason.

 

120G is a decent tank size to set up. Be prepared to drop a decent amount of money on proper equipment for a tank that size, namely a good skimmer. If you are doing a FOWLR tank, strong lighting won't be as critical as it would be with setting up a reef. Depending on the fish choices, you will want to export the waste efficiently through a sump/fuge. Heating and chilling that much water will also be an area of thought too. They are great to have though. Just go slow and don't cut any corners, no matter how much you start thinking "well this one is $100 less."