Re: Lighting for 90 gallon

[Bill Wichers <billw at waveform_net>]

> (two 48" bulbs and two 24" bulbs).  I am still a bit confused as to the whole
> T8/T12 thing.  I am not sure if both can be used in my lights.  The one light

T8's are 1" diameter, T12's are 1.5" diameter. The number is the diameter 
in eighths of an inch. T8's will generally give you more light for less 
wattage, last longer, cost less, etc... T8's are an all-around better light 
bulb to use.

You can normally run a T8 bulb in a T12 fixture. Worst case you overdrive 
the T8 a bit, which isn't really a problem -- it will just shorten the life 
of the tube a bit. Most fixtures that I have tried that can start a T12 
bulb will not have a problem starting a T8 bulb. I don't know about the 
other direction since I haven't tried it too often, but I suspect you would 
have the best luck using instant-start ballasts if you want to be able to 
use either T8 or T12 bulbs interchangeably in the same fixture.

T8's in 48" lengths are the commercial lighting standard now (and have been 
for some years now). As a result they are made in massive quantities and 
will be the cheapest lights for your tank. There is a wide selection of 
bulbs out there. People have had good luck with the GE Chroma 50's and the 
SPX50's from (GE? Phillips? Can't remember for sure). Chances are either of 
those will probably work in your existing fixture. If it doesn't you'll 
need to swap out your ballast which is going to be about $20-40 depending 
on what kind you get. As long as your current fixture uses bi-pin (2 pins 
about 5/8" apart) you'll be OK -- T12's and T8's both use the same bi-pin 
sockets. The older 1-pin (big 1/4" diameter pin on each end of the bulb) is 
much less common. Chances are that even if you need to swap out your 
sockets, they will be standard snap-in type sockets that you can get at 
Home Depot for a few bucks.

> with the 2 24" has T12s in it now the light made for 2 48" bulbs has no bulb
> in it and I don't know which it is supposed to have.  If I am going to use
> this for freshwater plants and fish which size bulb should I use (T8 or T12)
> and which K (5,000K, 10,000K, etc.)?  Specific brands and names would be nice
> to make shopping easier.  Keeping cost down would be nice too.  I do not
> particular like the yelowish lights, but if they are good for the plants I
> can probably mix them with whiter ones.

Anything over about 5000K-6500K is going to put you into the specialty 
aquarium bulbs which are FAR more expensive. The GE Chroma 50's can be had 
from Grainger for around $5 in low quantities (eaches) for a 5000K bulb 
last time I looked. If you're on a tight budget that will probably be your 
bulb. A lot of successful planted tanks live under lights like that. The 
lower color temperature flourescents usually look pinkish or greenish 
rather than yellowish. You may want to try using a few 5000K bulbs along 
with one or two 3000K-4000K bulbs (NOT the 4100K "cool white" bulbs 
though), something listed as a "daylight" with a low color temp. The mix 
may provide a blend of light that you'll find more appealing to the eye.

        -Bill

> Scott


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