Calculating Light levels

Discussion in 'Planted Tanks' started by Fishrone, Jul 28, 2009.

  1. Fishrone

    Fishrone

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    I was wondering if anyonw could help me with calculating light levels.
    I knw the usual dived the total wattagw by the total gallons, but an aquastar tube is 36w jus like a 36w standard cool white tube. how do u work out a lighting level using a kelvin scale because that is what is important?

    tx in advance
     
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  3. Dolphin

    Dolphin

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    hello and welcome to TASA!

    Please explain what do you mean by lighting "level"?

    The tube should have on it what Kelvin rating it is...
     
  4. sailing_derrick

    sailing_derrick

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  5. OP
    Fishrone

    Fishrone

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    What i mean is with all plant care sheets they tell you that u need "X"watt/gallon..
    now if i put 7 36w standard tubes in a 260 gal tank i will have approx 1w/gal. and the aquastar tubes are 10000K but also 36w.

    So i dnt quite understand how much light every different plants actually needs
     
  6. neilh

    neilh

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    36w is 36w, regardless of what colour it is. Light spectrum ie Kelvin is what gives you the difference in either plant growth or Coral growth, blue,white,red etc etc

    So if a plant requires 2w/gal, you'd aim to get as close to daylight tubes with the approximate wattage over your tank

    To confuse you even more, height of your lighting in relation to the water level has a huge effect
     
  7. Dolphin

    Dolphin

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    Ok, what you need to do is get a mix of 6500K and 10000-14000K lighting in there in the ratio of 2:1 (2 6500s for every 1 10000K). Typically you need to space them about 5cm apart across the width of the tank. For T5's to be effective they should be no more than 3" from the water surface. I assume your tank has a water depth no more than 60cm. more than that you typically need to get Metal halides or the more powerfull Geisemann T5's which are quite costly. This will then give you the lighting you need to grow most if not all plants.

    NB: T5's need to be setup and wired in a spefic way per the instructions on the ballast which specifies max wire lengths. Also you need a good reflector in the hood to maximize the light penetration.

    Perhaps tell us more about your setup and plants etc. Lighting is not everything as you might need CO2 in there as well...
     
    Last edited: Jul 28, 2009

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