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Re: Effective penetration depth of MH lights


Date: Sun, 7 Jun 1998 09:11:17 -0600 (MDT)
From: George Booth <booth at lvld_hp.com>
Message-Id: <199806071511.JAA28317@hpmtlgb1.lvld.hp.com>
To: Aquatic-Plants at actwin_com
Subject: Re: Effective penetration depth of MH lights

> Date: Sat, 6 Jun 1998 21:10:18 EDT
> From: Aquatect2 at aol_com
> I was wondering if anyone had a good feel for the maximum water >column
depth (surface of water to top of substrate) that 175 watt metal >halides
would effectively penetrate.  By "effective" I mean that high-light >plants
at the substrate such as dwarf chain swords (echinodorus tenellus) >would
-thrive-.  24"?  30"? ... more???  I'm thinking two bulbs over a 60" >long
by 24" wide tank.  

MH, FL, IN or whatever light will penetrate the water column of most any 
practical home aquarium just fine.  

The major problem is penetrating the "plant" column. As the tank gets taller, 
the taller plants tend to spread out and shade everything below them.
Increasing the amount of light or changing the type of light has little
direct effect in solving this problem. Brighter lights will get more light
to the substrate through reflections but will also be too bright for plants
near the top. 

The best solution for a tall tank is to find plants that tend to grow
up (val, bacopa, rotala, etc) for midground and background plants. Avoid
plants that spread (aponogetons, larger echonodorus, ludwigia
(especially!)).   Careful aquascaping and careful pruning are essential to
the success of a tall tank. 

George in Sunny Colorado


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