# Are bulb sizes interchangeable?



## tokyo (Jan 19, 2010)

I have a hood that I got used, it came with a 24" T12 already in it. I would like to buy a replacement bulb but can't find any 24" T12 bulbs. Can I use a 24" bulb of a different size, like a T10?


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## CrypticLifeStyle (Dec 14, 2009)

tokyo said:


> I have a hood that I got used, it came with a 24" T12 already in it. I would like to buy a replacement bulb but can't find any 24" T12 bulbs. Can I use a 24" bulb of a different size, like a T10?


As long as the Tube diameter fits & it's the same socket type sure...I dont know about T10's but i know T12's & T8's use a "G13 bipin/Single Pin/Recessed Double contact" , prob fair to say the T10 does as well...However T5's need a G5 bipin socket type...


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## Number6 (Mar 13, 2003)

the ballast may be the type that can power T8s or T10s as well as T12s, or it might not be. The ballast usually says on it if you can open the light fixture and read.

Otherwise, it's a case of put in the T8 and turn it on... if it lights, you're probably fine, If not, shut it off quick!


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## tokyo (Jan 19, 2010)

Number6 said:


> the ballast may be the type that can power T8s or T10s as well as T12s, or it might not be. The ballast usually says on it if you can open the light fixture and read.
> 
> Otherwise, it's a case of put in the T8 and turn it on... if it lights, you're probably fine, If not, shut it off quick!


What is the ballast? Is it the cylindrical starter in the light fixture? If so it says "4. 6. 8. 14. 15. 20W" underneath the brand name. Does this mean anything to you?


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## mg426 (Nov 24, 2009)

Take a look here
http://www.hellolights.com/index.asp?Pa ... tegory=759


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## CrypticLifeStyle (Dec 14, 2009)

tokyo said:


> Number6 said:
> 
> 
> > the ballast may be the type that can power T8s or T10s as well as T12s, or it might not be. The ballast usually says on it if you can open the light fixture and read.
> ...


The ballast will be the rectangular device inside the fixture housing...In short term it regulates the electrical current...The starter acts as a amplifier to ignite the gases inside the fluorescent tube which in turn creates the light...


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## tokyo (Jan 19, 2010)

mg426 said:


> Take a look here
> http://www.hellolights.com/index.asp?Pa ... tegory=759


Thanks, but I was hoping to try a Hagen flourescent bulb so I can have my LFS order it for me. That way I don't have to pay shipping since they already get a Hagen shipment in every friday.

I am currently using a Coralife 24" T12, but no one around here carries them.


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## tokyo (Jan 19, 2010)

CrypticLifeStyle said:


> The ballast will be the rectangular device inside the fixture housing...In short term it regulates the electrical current...The starter acts as a amplifier to ignite the gases inside the fluorescent tube which in turn creates the light...


Ok, I took apart the fixture and found a black box labeled "Transformer", I'm assuming this is the ballast you are talking about.

The label is pretty faded, but I can make out "FOR 1, 14, 15, 13 20W LP". The 13 may be an 18, and some of those commas may be periods. Is this helpful at all?


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## cjacob316 (Dec 4, 2008)

http://en.wikipedia.org/wiki/File:New_GE_Ballast.JPG

here is a pic of a ballast for a fluorescent light, note in the bottom left it says lamps/ 1 x 18 watt t-8/ 1 x 20 watt t-12


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## tokyo (Jan 19, 2010)

cjacob316 said:


> http://en.wikipedia.org/wiki/File:New_GE_Ballast.JPG
> 
> here is a pic of a ballast for a fluorescent light, note in the bottom left it says lamps/ 1 x 18 watt t-8/ 1 x 20 watt t-12


Mine did not have this info on it. Guess I'll just have to try a bulb and hope for the best.


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## cjacob316 (Dec 4, 2008)

what about going to home depot lowes or walmart, and getting a phillips, i know they make them in 6,500k which would be fine for an aquarium, they may have the correct size


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## bulldogg7 (Mar 3, 2003)

(big chain store) may have the 24" T12's in the pet section.


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## tokyo (Jan 19, 2010)

bulldogg7 said:


> (big chain store) may have the 24" T12's in the pet section.


I bought a GE _Aqua Rays_ 24" T12 today for 5 bucks from wallmart. Not exactly what I wanted, but will work until I can find another solution.

The ligtht is a little bit too purple for my taste, but at least its brighter than what I was using.


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## fmueller (Jan 11, 2004)

To the best of my knowledge, there is no such thing as a T10 fluorescent tube. What there is is T12, T8 and T5.

T12 is the oldest of these standards. The tubes are the thickest and least energy efficient. They run with a magnetic ballast ("cylindrical starter"), but can also use an electronic ballast, which looks entirely different.









_Two different electronic ballasts in T8 fixtures_.

T8 is newer and more energy efficient than T12. The tubes physically fit in the same fixtures as T12, but T8 requires an electronic ballast. Meaning if you have a fixture with electronic ballst you can likely run T12 or T8. With a magnetic ballast you are stuck with T12.

T5 is still newer and even more energy efficient. They are thinner then T8 and require completely different fixtures. T5 used to be a lot more expensive than T8, and IMHO 5 was not worth the bother for a long time. Recently prices for T5 have come down a lot, and they seem well worth looking into. I guess T5 is feeling the competition of LED lighting, which is the next big thing.

Frank


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## Number6 (Mar 13, 2003)

tokyo said:


> but I can make out "FOR 1, 14, 15, 13 20W LP".


Your ballast can run one 14w, 15w, 18w or 20W lamp. 
Highly likely it will not run a T8.

fmueller, there are T10 bulbs... rare, never caught on. There is also a magnetic ballast for T8 lamps as well... but these are the exceptions to the norm  
The norm matches up with what you wrote :thumb:


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## tokyo (Jan 19, 2010)

Number6 said:


> Your ballast can run one 14w, 15w, 18w or 20W lamp.
> Highly likely it will not run a T8.


I guess I will just stick with the cheap GE bulbs, they're not so bad, starting to grow on me. Someday I may buy a new light fixture which will allow me to use the higer end flourescent bulbs. But for now it's just not on my list of priorities.

Thanks for the help! It would have been a bummer to spend 20 or so dollars on a nice T8 just to find out that I can't use it. :lol:


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## fmueller (Jan 11, 2004)

Number6 said:


> fmueller, there are T10 bulbs... rare, never caught on. There is also a magnetic ballast for T8 lamps as well... but these are the exceptions to the norm
> The norm matches up with what you wrote :thumb:


Interesting. I've never seen any of those. You live and learn.

BTW - one of the disadvantages of smaller tanks is that hardware stores have a lot less choice in 2' and 3' light fixtures than 4'. For a 4' tank you can buy excellent lighting for next to nothing, and for larger tanks it really pays to make 4' lighting work for your setup. A new double strip 4' T8 fixture around here can be had for around $10 and two 6500K tubes for that fixture are around $7 ($3.50 per tube). That's what I have on my 75G, and I just sold an Amazon Sword plant from that tank that had take over more than half of the tank :thumb:

I wish cheap lighting like that was available for 2' and 3' tanks, but I haven't found it yet.

Frank


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