# T8 or T5?



## HMlairy (Jan 22, 2011)

Hi, 
I'm completely new to florescent tubes so sorry if these questions are stupidly simple but I was wondering:

1. What are the differences between T8 and T5 bulbs? Benefits/negatives

2. Which would you most advise me to get for my 30inch long, 15 inches tall, 12 inches deep aquarium in which I wish to potentially grow plants?

3. Does a T5 tube need a different starter unit to a T8, and visa versa?

4. Can any UK residents suggest a decent starter unit for the tubes to use?

Sorry if these seem dim and not worth your time but I've always wanted decent lighting but haven't got a clue what to get over the internet.

Feed back greatly appreciated.

 Thanks

PS What wattage would you suggest as well?


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## Byron (Mar 7, 2009)

> 1. What are the differences between T8 and T5 bulbs? Benefits/negatives


Some aspects of this question will be answered below, but first the "T" number is simply the diameter in 8ths of an inch, so a T8 is 8/8 or 1 inch diameter, and a T5 is 5/8 diameter. But this is only the physical size, more below on the difference.



> Does a T5 tube need a different starter unit to a T8, and visa versa?


Yes. The fixture for T5 only takes T5 tubes, and similarly for T8. Here I'll explaion a bit more on the light. T8 are the "standard" fluorescent tubes, a newer replacement for the original T12 tubes that are being phased out. T8 are more efficient, producing equal or sometimes more light with less energy (watts). T5 are more advanced still, producing considerably more light than the same length tube of the same type in T8 [type referring to spectrum]. But this is where it gets tricky, as I'll go into more in the last bit below.



> What wattage would you suggest as well?


This is rather irrelevant. Watts is simply the measure of the amount of energy needed to light the tube. For example, the 48-inch T12 tubes were 40w. The first T8 tubes were also 40w (48-inch tubes still). But now they are making them in 32w, but they produce the same light. More efficient, less energy.

When it comes to T5, they are different wattages again. But the main thing to remember is that T5 comes in NO (normal output) and HO (high output), and I think now also VHO (very high output). The NO is basically the same as the T8 in terms of light intensity from the same length and type of tube. The HO is 1.5 to 2 times the light intensity. [The VHO I'm not familiar with, they are more for marine tanks growing corals.] So you can see that having 1 T5 HO tube is comparable to almost 2 T8 tubes, again with same length and type.



> Which would you most advise me to get for my 30inch long, 15 inches tall, 12 inches deep aquarium in which I wish to potentially grow plants?


You could do OK with a single T8 tube which would likely be a 24-inch for this sized tank; I have this on my 29g. But it is at the very lowest level, and frankly I would suggest something else. With a high-quality tube like the Life-Glo I can grow some plants OK in this tank, but I know it is very marginal.

A single tube T5 HO tube would be OK, for low and moderate light plants, and floating plants. High light plants would struggle and likely not last.

A dual tube in T8 would be fine. I would not get a dual T5 because with HO tubes that would be too much unless you intend diffused CO2 and significant nutrient supplementation.

Hope this helps.

Byron.


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## fish monger (Dec 29, 2011)

The dual tube T8 would be my choice also. If you don't mind paying more up front, a dual tube normal output T5 would be good and save on energy costs in the long run.


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## HMlairy (Jan 22, 2011)

Thanks very much, just what I needed


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## HMlairy (Jan 22, 2011)

Unfortunatly I don't think I can install dual tubes into my hood as there looks like there is only room for one tube plus clips.
But I will have a look into T5 single tube as I am not being too ambitious in my first stock of plant


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