What pc bulbs to buy?

reb

Member
I have a custom sea life 48" 4x65watt fixture. I need to buy replacement bulbs for my 75 gal reef tank/ all sorts of different corals. Right now it came with 2 10000K and 2 actinic. When I look to buy I see daylight bulbs of 10000K and 6700K. What would be best. Also I see 460n actinics and 420n actinics and one that combines 460n and 420n in the same bulb. What would be best. They are 65watt square pin. Thanks
 

nyreefer

Member
You can get (2) 10,000K bulbs and (2) Actinic 03 bulbs or (4) 50/50 bulbs which are a combo of 10,000K and actinic. Make sure you get the true actinic 03 and not the 6700K actinics.
 

robchuck

Active Member
Most reef tanks that use daylight bulbs use 10,000K bulbs. If you're happy with the look of your current 10,000K bulbs, I would recommend going with two of those and two actinics. Otherwise, the 6,700K bulbs would give a more yellowish appearance.
As far as the actinic bulbs go, I would definately get the ones that peak at 420nm. This wavelength is where zooxanthellae reaches its peak abosorption. The 460nm bulb (sometimes referred to as 7,100K blue) wouldn't do much more than serve to asthetically soften the harsh visual impact of the daylight bulbs.
So, my recommendation would be to replace the current bulbs with two 10,000K bulbs and two Actinic 03 bulbs that peak at 420nm.
 

reb

Member
how do you know if they are actinic 03. they never tell you in the description.
 

robchuck

Active Member
Actinic 03 describes the type of phosphors inside the bulb. A true actinic 03 bulb acheives the blue light through it's phosphors.
Wheras a PC bulb that puts out blue light by having the tube tinted uses regular fluorescent phosphors, where the tinting even blocks out some of the PAR we are trying to deliver to our corals. Unfortunately, these bulbs aren't of much benefit to our reefs, but are still often marketed as "Actinic" bulbs.
The most important things to look for when shopping for actinic bulbs is to see what types of phosphors are used and to find actinic bulbs that peak at 420nm.
 

dacia

Active Member
The bulbs that I use in my 2x65W system are 1 6700K/10,000K white and 1 Actinic 03/7100K.
Would you recommend the 10,000K white and actinic 03 over the dual bulbs that I currently use, or are the ones that I use fine? My reef is doing quite well, but I am always looking for ways to improve it.
 

robchuck

Active Member

Originally posted by Dacia
Would you recommend the 10,000K white and actinic 03 over the dual bulbs that I currently use, or are the ones that I use fine? My reef is doing quite well, but I am always looking for ways to improve it.

The 10,000K/Actinic 03 combo is the ideal PC combination in my opinion and might give you better results if you were to switch to this combo.
But you mentioned that your tank is doing quite well under the current lighting, so my thinking then becomes "why change what's already working?"
 
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