Re: NANFA-- 135 gal. Freshwater Tank

Bruce Stallsmith (
Mon, 02 Feb 2004 18:51:15 -0500

OK, and I went back to another source, too, Wetzel's book "Limnology" to see
what the received wisdom about submerged macrophytes (big, real, plants) is
for temperate natives. A key point he makes is that "submersed macrophytes
are distinctly shade-adapted with high concentrations of pigments and
low-light compensation points of photosynthesis, commonly at 1-3% of full
sunlight." Their light physiology is comparable to shade-dwelling land
plants, like most ferns or Selaginella. They often suffer from
photoinhibition at higher levels of light, i.e. there's such a thing as
hitting them with too much light.

I realize that this is a very different view than coral reef tanks, where
the algal systems need to be driven with really intense lights, or even the
standard tropical set-up. So I'm happy for the moment to be using 460 nm
actinics, and hit the plants with a steady source of blue/green wavelength
light. I'll soon know if this set-up is good for good ol' photosynthetically
active radiation.

--Bruce Stallsmith
Huntsville, AL, US of A

>From: "Todd Crail" <>
>To: <>
>Subject: Re: NANFA-- 135 gal. Freshwater Tank
>Date: Mon, 2 Feb 2004 18:18:54 -0500
>You know I think I can do this really quick. :)
>Get a lamp color between 4000K and 6500K and the plants will do just fine,
>and will be well within their zone of photoreactivity to outcompete the
>There's nothing to analyze there!
>How much carbon and micronutrients you have to provide to meet the uptake
>depends on the amount of PAR (Photosynthetically Available Radiation) you
>are providing. This is a measure of intensity.
>If you have more PAR than available carbon and micronutrients, you will
>the door for algae to participate, regardless of what lamp color you have.
>If you have less PAR than available carbon and micronutrients, uptake may
>not be fast enough due to an "energy input" deficincy to use the phosphates
>and nitrates our aquariums produce, and you will open the door for algae to
>participate, regardless of what lamp color you have.
>High Color Temp has lower PAR values as the wavelengths are long and
>infrequent. Low Color temp has higher PAR values as the wavelengths are
>short and more frequent.
>Flourescent and Compacts have lower PAR values because the wattage is
>derived along a tube. Metal Halide has high PAR values because the wattage
>is derived from a tight source point.
>Yes, it's a balancing act, and you have to figure it out yourself. No one
>can teach this, regardless of how many act like they can.
>And more info to arm you...
>At similar wattages, Metal Halide has a very short but square intensity
>footpint... Flourescent lamps have thin but long intensity footprint.
>Flourescent lamps are good for achieving a like lower intensity across a
>large area which is good for most submerged plants commonly found in our
>Metal Halide is good for achieving something that looks like sunlight, can
>be filtered by emmergent plants and still reach the submerged plants below,
>reflected off of wood to produce shadows, and meet a whole realm of plant
>community requirements.
>Todd's book of lighting in 8 minutes! Heck yeah! :)
>Hope this helps..
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