What Light Through Yonder Aquarium...

"It is the east, and probably isn't the sun. "

"What is a better light?"  That's called an "open question". Better for what? Your wallet, your plants, your fish, your electricity bill... etc. But I will endeavour to give a summary.

Basically, the difference between T5 and T8 is the amount of light they output.  A T5 will produce approximately twice as much light per foot as a T8. A High Output T5 about 3 times as much. This is a very rough and ready guideline.

There are other differences, different fittings, different electronics, different power etc. Colour however is determined by the type and mixture of the chemicals that coat the inside of a fluorescent tube. They are called phosphors if you are interested. The colour of a particular tube is measured by what is called it's colour temperature. You can get sensible coloured tubes of either T5 or T8. By sensible, I personally would stick to lights having a colour temperature around 6500K. These are daylight white tubes, significantly higher and they will have a red cast, significantly lower, a blue cast.

I can't remember whether you have live plants, but since you asked I will assume you do. "Better" is such a subjective term; Which is "better" depends upon what you wish to achieve and with how much aggro. Talking very generally here, a tank with 2 full length T8 tubes will produce enough light to keep what is called a "low-tech" planted tank. This involves growing "easy" plants and not having to bother with adding CO2. 2 T5 tubes will mean you can grow more dificult plants, but you should start to think seriously about adding CO2. Any more than 2 T5 or 2 T5HO and you really have to be adding CO2.

And then there are LEDs.........

If you require a more detailed answer, provide a better question please.

Note:Edited to add red bit

"Good night, good night! parting is such sweet sorrow"

How rude! Fancy taking so-oo long to reply to you.....my sincere apologies, Steve Between work, summer visitors, airport runs and generally crap broadband, I'm afraid my TF time has been neglected.

Anyway, thank you for your help. I am just researching for my new tank because I'd like to get everything right to start with.
Yes, I do have live plants and don't really want to go down the CO2 route. By the way, why do you have to add CO2 if you choose to have T5 tubes? That's probably a numpty question, but hey! that's what I am
Actually, I am interested in the phosphers and I agree with you. I would like a daylight colour and not a blueish or reddish hue to the light.

I didn't make my question very clear....sorry I did mean better, as in would one or the other give a more natural light and not cast a strange tint on the tank and it's residents and which sort would the fish and plants be happier under.

So, is that a 'better' question?

Thanks Steve, for you previous prompt reply and apologies again for my tardiness

Ah...now I never said I had a life

Thanks for that explanation, Steve...and it all made perfect sense to me as well....I must be having a good day Quite amazing really as since Saturday night, I have had the grand total of 9 hours sleep!
I am blitzing the kitchen at the moment...well, actually at the moment, of course, I am writing this...but back to the kitchen in a minute, then I'll be heading off for some kip....sods law...when I get there I won't be able to sleep

I shall definitely make sure that my new tank has 2x T5 lights and the 6500K tubes you have advised. So, that's my substrate sorted...thanks to Colin, and now my lighting. Next step, I think will be to think about the decor and planting I want.

Thanks for your help, much appreciated