This site is supported by the advertisements on it, please disable your AdBlocker so we can continue to provide you with the quality content you expect.
  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

quick lite question..

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

  1. anov50

    anov50 Lifetime Members
    Lifetime Member

    May 8, 2011
    Likes Received:
    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
    Lifetime Member

    Jul 6, 2009
    Likes Received:
    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
    Lifetime Member

    Oct 8, 2008
    Likes Received:
    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.

    Santo Domingo

Share This Page