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quick lite question..

Discussion in 'Lighting' started by anov50, Jun 19, 2011.

  1. anov50

    anov50 Lifetime Members
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    I have a 4 bulb 48" t5 HO fixture over a standard 75gal ( 48"x18"x21"). Atm i have the fixture 6" above the water line (about 25" above the substrate). I dont have a way to measure PAR atm but im wondering if anyone can give me a rough idea how high to suspend the fixture to get the ideal light level (50 micromuls i think) at the substrate?
     
    #1 anov50, Jun 19, 2011
    Last edited by a moderator: Jun 19, 2011
  2. dutchy

    dutchy Plant Guru Team
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    Based on measurements with my tank, also with 4 rows of T5, gives me 90 micromols at 20 inch above the substrate. PAR drops off @ 10 micromols every 4 inch. So to get at 50 you would need a distance of @ 36 inch above the substrate.

    You could also try to just use two bulbs and keep them 4 inch from the water surface, which will give you a nice energy saving.
     
  3. pepetj

    pepetj Lifetime Members
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    It's hard to tell without measuring... different lamps provide different readings; I get different readings between the moment after a huge water change and the moment before the next water change also. Water turbidity interferes with light a good deal; quality of reflectors also makes a noticeable difference.

    I would move from less to more slowly while observing plant growth and overall tank conditions. Less light makes it easier to manage than more light.

    Pepetj
    Santo Domingo
     
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