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Holy Over Exposure, Batman!

George wrote (though I've changed the order somewhat):

>As I read some of the posts that mention algae problems, I am boggled at the 
>amount of light being used. One gentleman wrote me and had 110 watts (CF) 
>over a 
>20 gallon tank. Holy Over Exposure, Batman!

I agree completely.  I have yet to meet a plant that I couldn't grow at @
3w/g where light levels were the problem.  I can make an argument for light
levels up to 3 w/g depending on the circumstances, as I'll get to later.
But I think if people can't grow any commercially available plants at 3w/g
or less, they need to look elsewhere for the problem.

I think that it's _possible_ to manage systems with more light, but why?
The system is less stable, more prone to algae problems (IMO, BECAUSE it's
less stable) and costs more to run.

>I've been hugely successful with 1.6 watts per gallon of FL light using
>and Penn Plax Ultra Tri-Lux bulbs in fixtures with typical reflectors placed 
>about 4" above the water. And these are 48" bulbs in a 60" tank! 

>I would like to see a discussion on two topics: 

>1) What level of lighting do the experts use (Tom, Roger, Neil, Karen, Erik, 
>Diana, Charley, Jon, ... you know who you are)?

I choose to use a few more watts over my fluorescent lit tanks, but not
anything like the numbers I see thrown about from time to time.  I use 6 4'
T-8 bulbs over one of my 75G tanks, for a total power useage of 180 watts
for a total of 2.4w/g.  My other tank has two NO fluorescents (because I
haven't gotten around to changing the ballast yet) and 2 T-8's, for a total
of 140 watts, or 1.87 w/g.

I can grow even the highest light plants in the tank with the 6 T-8's, as
long as I don't let the taller plants shade the ones below. (I actually
think _this_ is the biggest light limiting factor in my tanks)  In the tank
with the 4 bulbs, I have not been successful with some of the higher light
plants, like R. macrandra, but there are other factors that are different
too... That is my only Flourite rather than laterite tank, which _may_ be a
factor.  But a bigger factor is that the plant mix is _very_ different in
that tank.  There are other plants, including a very large nymphaea that
might well be out-competing their neighbors.  The flip side is that some of
the slower growing plants simply glow in this tank.

>Since the MH bulbs in the 120 are suspended above the water, the amount of
light at the 
>water surface is the same as in the FL tanks (15,000 lux) and is not
really like "2.9 

I have 2 Hamilton 175W pendants over my 120G also.  Like you, I have had
very, very good growth at that light level.  I do find that I need to place
plants strategically with this set up, though.  There is a dim space in the
middle where I can't put my more light-loving plants.

I do think that with less efficient forms of light, you can need to throw
more watts at the tank to get the same result, but again, I don't, even
with these less efficient types of light see the need to go above 3w/g.  In
comparing results with various plants with Neil, it also seems that some
high-light plants need more MORE light in the harder water I have than they
do in his much softer water.

>2) Why do many of you think "more is better"?  IMHO, more is never better.
More is trouble. Just enough is better.  

I want to know the answer to this one too.<g>