does T5 has a maximum effective depth?

Discussion in 'Lighting' started by jarthel, 16 Nov 2009.

  1. jarthel

    jarthel Member

    Messages:
    212
    I'm considering 6x 4W T5 HO for a 70cm (h) tank. I plan to have a 8cm thick substrate. Will this work? thank you
     
  2. plantbrain

    plantbrain Expert

    Messages:
    1,949
    Yes, I have 1.8W gal at 80cm from the bulb to the lower plants without any issues.

    You have more than enough light, maybe more than you bargain for.

    Regards,
    Tom Barr
     
  3. jarthel

    jarthel Member

    Messages:
    212
    thank you for the reply :)

    just a question again if you don't mind: you said, 6x is a lot. Is there some sort of calculator that I can use? I do not intend to plant any plants that require bright lights.

    thanks again
     
  4. George Farmer

    George Farmer Founder Staff Member

    Messages:
    7,091
    Location:
    Cambridgeshire
    Do you mean 6 x 54w T5? 4w lamps are very small...

    I had success with 2 x 54w T5 over a 70cm tall tank (370 litres). With good reflectors 2 x T5 is all you generally need for most plants, even at 70cm. Good nutrients and circulation are also very important.
     
  5. jarthel

    jarthel Member

    Messages:
    212
    yeah. I meant 54W. just want to clarify: you meant 2x T5 HO. right?

    thanks again
     
  6. George Farmer

    George Farmer Founder Staff Member

    Messages:
    7,091
    Location:
    Cambridgeshire
    Yes, HO T5. :thumbup:
     
  7. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

    Messages:
    8,953
    Location:
    Chicago, USA
    I'd be much more worried about how to get enough CO2 to penetrate down to the bottom of a 70 cm high tank while using such high spectral energy levels. :silent:

    Cheers,
     
  8. jarthel

    jarthel Member

    Messages:
    212
    I'm a first timer and I was just considering the equivalent power output based on 2x 150W halides. :)
     
  9. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

    Messages:
    8,953
    Location:
    Chicago, USA
    Well, this is THE single biggest mistake first timers make. Lots of light without considering the implications of CO2 and nutrition results in algal blooms. I don't think you want to spend your time cleaning algae from those 70 cm of glass every day right? First timers need to be much more concerned about having sufficient flow in the tank to deliver CO2 and nutrients and they need to have a plan for how to distribute that flow. Lighting is easy. Plants don't require nearly as much lighting as people seem to be hypnotized to believe. I use loads of lighting but that requires loads of CO2, flow/distribution and nutrients. Have you thought about your CO2 injection methods, i.e. whether you need to use multiple injectors on this sized tank, or whether to use external versus internal diffuser? This should be at the very top of the list for any tank, but especially for large tanks. Have you thought about water changes? With such high energy levels you'll need to do large and/or frequent changes so that factor might affect hardware choices and perhaps even tank placement.

    There are so many things to think about and there are so many potential problems that your lighting choice will only exacerbate....

    Cheers,
     
  10. jarthel

    jarthel Member

    Messages:
    212
    I am thinking of getting a 4x 54W (maybe 3) and leaving only 2 bulbs in there for now until I ready to "walk". I want to learn how to "crawl" for now. This thread opened my eyes! :D

    Thanks everyone!!! :)
     
  11. plantbrain

    plantbrain Expert

    Messages:
    1,949
    4x 54 watts is what I have on a tank that is 120cm x 60cm x60cm at 80 Depth(lights are about 20cm above the tank).

    They are spaced out almost 35cm apart in pairs, so there is some good sized light angles going on that make the tank look fullers and grows dense than a point source might or a single high intensity bulb, in otherwords, the light spread is more even.

    If you have humble species goals, then stick with no more than this for T5.

    Even with nice plant species, I've yet to find any species that does not grow well due to light. It's always something else for a reason why the plant does poorly in this tank.

    Regards,
    Tom Barr
     
  12. George Farmer

    George Farmer Founder Staff Member

    Messages:
    7,091
    Location:
    Cambridgeshire
    In response to a PM, but it's worth sharing.

    You should be able to grow most foreground/carpeting plants with 2 x 54w T5, providing CO2/nutrients and circulation are up to scratch.

    Because of their position in the aquarium, low plants tend to receive the least amount of flow and CO2, so consider this when positioning your filter outlets etc.

    Some foreground plants are more demanding than others too, so consider species selection too.
     
  13. jarthel

    jarthel Member

    Messages:
    212
    So I can exclude HC and glosso. right? thanks again
     
  14. George Farmer

    George Farmer Founder Staff Member

    Messages:
    7,091
    Location:
    Cambridgeshire
    Not necessarily. If they're not shaded by other plants, and you have good CO2/nutrients and circulation down there then you may be ok.
     
  15. jarthel

    jarthel Member

    Messages:
    212
    thank you very much :)
     

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