[APD] The right lights

[Gwmangen at cs_com]

George Mangen wrote:

> The formula I'm using for light is one that I found in
> the archives:
>
> 1. Multiply surface area by distance from light source
> to substrate in inches. . . . 

Scott Hieber responded:

Uh, did they factor ambient light, temperature, shadows cast by fish swiming 
by, etc? ;-)  Just kidding, but my point is that this is way too complex for 
aquatic gardening. It's like measuring in nanometers how much to trim your 
fingernails. Diff plants need diff amounts of light. And diff tanks will behave 
diff because of all the factors at play, not the least of which is the gardener 
and how she or he deals with the tank (doses, cleans, stocks with fish, stocks 
with plants), the particular light bulbs, reflectors, etc. The best thing is 
to just follow a simple rule of thumb and adjust accordingly to suit your own 
needs. A good place to start is about 1.5 -2 wpg for slow growing tanks and 
2-3 for faster growing tanks with added CO2. Successful tanks have been 
maintained at 1 wpg and at 4, 5 and even 6 wpg --although anything above 4 is a speed 
zone I personally don't care to enter. So there is no single right amount of 
light.


George writes:

The formula is definitely out to lunch.  I just put a 5 watt flourescent 8 
inches over the substrate (sorry, I can't help it) and contrary to the formula, 
it's bright like Scott suggested it would be with his 2-3 watts for faster 
growth. The CO2 is at 25 mg/l right now and the java fern is going crazy bubbling 
like I've never seen it before.  The anubias n. and bolbitus h. look just as 
miserable as they have always been.  I think this is because the java fern has 
a greater critical mass.  The anubias n. is down to its last two leaves after 
the rhizome disintegrated.  The bolbitus, forget it, I can't even begin to 
understand what that plant is doing.  I think my pH might be too high for it or 
something.

Anyway, the fish (I added one to help keep the plants happy) is a little 
distressed by the bright light so I'm going to move the flourescent light up to 
16" over the substrate and turn the incandescent light back on because I think 
the combination of lighting will be good.  It's interesting how much more 
instructive the plants can be than the formulas.

Sincerely, George Mangen

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