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Re: [APD] Re: Fluorescent lights close to the water surface -- or -Heated debate


Thanks for pointing out the heat issue.

However my question was more focused on how to increase the intensity of light provided that I use normal T8 fluorescent and that the aquarium cover is closed. There's certainly a limit to the number of T8's that I can put side by side if there's a reflector. I would say that for my 20 inch wide tank I can stuff up to 6 such reflectors. Now the question is whether lowering them would increase or decrease... Incresase because of the 1/R law and decrease because light shall escape through the glass because of the angle...

And yet another idea is to just put those FLs without reflectors and rely on the fact that the hood is a white reflective formica.


From: "S. Hieber" <shieber at yahoo_com>
Reply-To: aquatic plants digest <aquatic-plants at actwin_com>
To: aquatic plants digest <aquatic-plants at actwin_com>
Subject: Re: [APD] Re: Fluorescent lights close to the water surface -- or -Heated debate
Date: Thu, 29 Jan 2004 03:18:27 -0800 (PST)

Rememeber folks, the amount of heat that a lamp gives off
is essentially the "wasted" input energy that isn't going
to visible light.  Fluorescents are generally just a tad
less energy efficient than MHs. So the type of lighting (MH
vs Fluorescents) won't necessarily make much, if any, diff
in heat, watt for watt. The heat is more concentrated with
MHs but depending on your ventilation methods that might
not make any diff at all.

As a somewhat sloppy but ready-at-hand way to estimate the
heat from you lamp, take the rated input energy and
multiply by 0.65; that's the input energy going to heat,
give or take, for MHs and fluorescents.

Ime, raising the bulbs higher from the aquarium by placing
them higher within the hood, doesn't make a lot of diff.
Raising the hood does make a diff because it allows more
heat to "mix" into room air instead of going into the
aquarium first.

Also, what can make a very big diff is to use vented hoods
like the enclosures on the AHsupply.com web site. Those
relatively large vents that run the length of the hood
allow a lot of heat to escape via convection provided one
allows a point of entry for room air near the bottom of the
hood -- for example, raising the rear of the hood up off
the glass 1/8" or 1/4" or putting vents in in the side
panels of the hood close to the bottom. In many cases, I
think fans can be avoided entirely this way.

Scott H.

Scott H.
--- Dirk_Matthys at toyota-europe.com wrote:
> You may want to consider the impact of added heat.  I
> have 75 G with 4 X T8
> 58 W. They are very close to the water surface ( 1 inch
> or so ) and they
> can replace my water heater during the day time,
> temperature will rise 1-3
> degrees ( depending on the room temperature ). I had to
> build in a
> ventilator to keep the water from becoming too hot in the
> summer because of
> this. Previously the lamps were more than 2 inch from the
> surface and I had
> no heating issues.
> If you are going to fit 6 or 8 in a hood , it's going to
> be a lot of heat,
> even with fluorescents.

===== S. Hieber

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