50/50?

Bulb colors are essentially going to dictate what things look like...not intensity, and the actual spectrum emitted that's usable for plants/corals can be much different. In that sense, color temp is deceiving.

The 50/50 is going to look more white/blue because of the 10000K/actinic mix. However it is marketed for coral more specifically because it's deeper in the blue end. The colormax is probably a warmer color...the T5 colormax bulbs are pinkish.

If it's a twist-in CFL fixture (not pins) I'd say save some money on bulbs and go with a daylight spiral CFL that you can find at any store with a home improvement section. Just find whatever fits in your fixture.

I have a 29 gallon tank that I have been experimenting with on lighting. I am using 2x18w 6500 CFLs currently and my plants are looking good with minimal algae growth. I have tried higher wattages and warmer specturms (2,700k, 5,500k), but at 23inches from the substrate and no CO2 it just amounted to a lot of algae growth. I would say if you have an under 30 gallon low tech tank then 2x 18watt CFLs (regular ones from the hardware store or Walmart) should suffice IMO.
P.S. this post in planted tank forum is more about PAR but I found this link that jpappy shared very informative as an introductory read on photosynthesis and light spectrum. http://www.plantedtank.net/forums/showthread.php?t=184368

captmicha said:

I'm having trouble finding mini bulbs at the 6500K temps. Might have to order them online. I thought these particular bulbs might be better. Guess not.

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Try HD and Lowe's. Look for the ones marked, "Daylight". Sometimes the color temp isn't marked on the package but of those that advertise both, I've found that the lamps which are advertised as "daylight" are typically in the area 0f 6500K.

Mark

"day light" can also be full spectrum or 5,500k which well be bennificial to plants but not as complementary to the color of the fish IMO. 6,500k puts out a noticeable difference of brightness that helps to illuminate your fish and scenery

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captmicha said:

The HD's in this area are useless! Lowes is a trek so I usually wait until I have to get a few things. Looks like it's getting to be that time. Does the bulb being spiral REALLY make all that much difference vs. straight pin? If the reflector reflects it all back into the tank, what difference does it make?

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I'm a bit confused, are these "screw in" fixtures or do they have pins?

A spiral fixture would probably be less efficient than more horizontal bulbs due to restrike...but they are certainly less expensive and easier to find in my area. If not for you, then it may not be a big difference.

My main point is to not worry so much about the color bulb unless you would like a certain "look" to the tank. The plants will do fine with just about anything within the visible spectrum unless you're looking at very quick growth with needier plants.

I grew many medium & a few higher light plants with screw in CFLs over a 10g with no CO2. I don't remember the size, it was the highest wattage Walmart Daylight 6500k that would fit in the fixture. They also sell (or did) thinner non-spiral CFLs in the pet dept that might work for you but they were more expensive per bulb & I don't know the spectrum.