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[APD] Re: Let there be light

Now, I am still very much inexperienced in the world of the planted
aquarium, but I thought I would add some data to the whole debate over the
amount of light one needs in the tank.  Now, I may be overestimating the
lighting requirements of these plants, but it is based on the general
consensus from numerous sources...so by all means let me know if the results
are not somewhat surprising (which of course, as a newbie, they are to me).

Approximately 15.6 gallon tank, 14" tall
Laterite underlayer, occasional Pant Gro liquid iron supplement
Aquaclear 150 filter
pH: 7.2
GH: 120 mg/L, KH: 110 mg/L
CO2: homebrew, approx. 1 bubble/6 secs.  approx. 7-10 mg/L.
Lighting: 15 watt T8 PowerGlo with mirrored tiles glued to hood behind light
as reflector.
Plants: Hygrophila corymbosa siamensis, Cryptocoryne...lutea (maybe?),
Ranunculus limosella, Egeria densa, Java moss, Ludwigia Repens.
Only one fish and two shrimp at this point. (going to begin stocking very

- I was told by numerous sources that ludwigia repens is a tricky plant to
grow without at least medium lighting (and apparently slightly less than 1
wpg is low lighting), especially if I wanted the red to be apparent.  What
surprised me was the fact that after maybe two weeks the ludwigia stalks
have grown close to an inch, and are a gorgeous rich red colour that shows
through even on the top of the leaves.  They weren't like that when I bought
them.  And only a couple of leaves at the very bottom died and fell off.
'Leggy' was what I was told to expect.
- I was also told the ranunculus would probably croak, as it is quite a high
light demanding plant.  It's going strong, although I haven't noticed much
growth (it is a slow grower, I know).  I would say it's definitely put down
roots (as I've not had to replant floating bits for some time).
- The other plants are ok in low light.  The only strange thing I've seen is
the Hygro has developed ruddy reddish colour at the leaf tips and somewhat
down the edges (compared to the old tank they were in which was incandescent
light (5wpg), and the leaves stayed a uniform green.

Now the factors I figure help: shortish tank, reflector (though mirror is
apparently not as good as mylar or white paint), high intensity bulb, CO2
and laterite.  Still I would have thought the lighting to be insufficient.
I followed the "never know 'til you try" approach, and was nicely surprised.

So what does that say for the lighting?

>Message: 6
>Date: Tue, 21 Sep 2004 00:23:27 -0700
>From: "Steve Pushak" <teban at powersonic_bc.ca>
>Subject: [APD] let there be light!
>To: "APD" <aquatic-plants at actwin_com>.
>The question "what is the best bulb" is ambiguous because the criteria
>for "best" is not given. There are a number of ways to rate bulbs:
>1) efficiency
>2) intensity
>3) operating cost
>4) spectral distribution
>The most important consideration is not the choice of lamp but rather
>the efficiency of the reflector. As Thomas has pointed out, #4 is a
>matter of aesthetics and has negligible effect upon growth. There is
>probably a measurable effect however for our concerns its so small as to
>be unimportant. For all other effects, the efficiency of the reflector
>greatly improves the cost performance. By using high efficiency
>reflectors, we could use a SINGLE (!) FL lamp to light an aquarium and
>achieve consistently good growth for the majority of conditions.

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