How much difference between T8 and T5?

Discussion in 'Lighting' started by sari, 24 Sep 2008.

  1. sari

    sari Member

    Messages:
    76
    Location:
    Basingstoke, U.K.
    Hi guys,

    just joined the forum and would like some answers already... Everything is looking good so far and have found loads of new info already!

    I have a Juwel Rio 125 that I'm setting up at the moment. It has standard lighting unit with 2 18 w T8 fluorescents in and I am looking into different options for the lighting in the future. For the moment, if I was to get a Juwel T5 unit, how much would the light increase? I have read that the output is 150% compared to normal T8 bulbs so with reflectors, the output should be many fold more efficient compared to T8? So 2 T5 should be 2-3 times more efficient compared to T8? The wattage only increases from 36 to 48 so figuratively the difference isn't huge.

    Any comments welcome!
     
  2. JamesC

    JamesC Member

    Messages:
    1,276
    Location:
    Bexley, Kent
    As a rough guide T5 tubes around the 18 Watt figure are about 35% more efficient than equivalent T8 tubes. But at around the 54 Watt mark this figure comes down to about 15% more efficient.

    Reflectors don't come into it as it's total light output that is measured and not how it is reflected. Both T8's and T5's can be fitted with reflectors. Where T5's beat T8's is with intensity. As light output per area of tube is that much higher they appear that much brighter and are able to penetrate the water better.

    James
     
  3. Ed Seeley

    Ed Seeley Member

    Messages:
    3,262
    Location:
    Nottingham
    You will also get a slight advantage with T5s and good reflectors in reducing the restrike. This is where light produced by the bublb is reflected back into it and wasted. With T5s their slimmer profile means less area for light to restrike and a good (ideally gull-wing) reflector will reflect light away from the bublb and into the tank meaning you use the light produced more effectively. How big a difference that makes is anyone's guess as, as James said, it isn't taken into the calculations.

    Also, for the standard T8 fittings you can get T6 bulbs which will fit straight into it and are more efficient that T8s (but not quite as good as T5s if I remember rightly). I have these in a Juwel unit on one of my tanks and they certainly kick out some light!
     
  4. sari

    sari Member

    Messages:
    76
    Location:
    Basingstoke, U.K.
    Thanks for that guys! I might look into the T6 tubes since the T5 unit with bulbs would come to a lot of money. The existing unit is perfectly ok and eventually once I sort co2 out, I can add extra lights for the tank. :idea:
     

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