Re: [APD]WPG rule

["S. Hieber" <shieber at yahoo_com>]

--- John Wheeler <jcwheel76 at yahoo_com> wrote:
> FWIW, I find on
> smaller tanks that the more light I use, the better
> the plants look without any other changes. Algae isn't
> a concern either.... 

A rule of thumb -- the more light the better?  ;-)
 
> No one seems to notice that coverage is really the
> critical factor. As long as the tubes that best fit
> the tank footprint are used, and you use enough to
> create an even coverage of the top of the substrate,
> it's enough light. 

Now that's a new rule of thumb, I think. Not sure if it
works equally well for Halides, PCs, and NOs, etc.

> Who cares how many watts they are
> or how many exact gallons your tank is unless it's? 
> 

Okay, now I'm pretty sure I disagree. I find it hard to
believe that wpg (or any other halfway decent measure of
output) doesn't matter so long as you're getting coverage. 
Halides, NOs, HOs, PCs, reflectors, no reflectors. I think
it's not just a matter of coverage but coverage with how
much. 

Otoh, if the supposition is that if you use PCs *and* get
even coverage, if that works out then I'll bet you're in
the roughly 2-4 wpg range on most tanks and the rules of
thumb are jsut as applicable as mere coverage. I never did
the math to see if that conversion works -- but I wouldn't
be totally surprised to see that it does. I would be
surprised to see that it works for other kinds of bulbs as
well.

However, I find that with my tanks, all of them conentional
in size in shape, I have the option of adding more or fewer
rows of bulbs, greatly altering the WPG, plant growth. I
can put one or two 55w PCs on my 29 gallon and the coverage
isn't much better with two (it's almost all entirely
ovelap) but it's a lot brighter and the plants seem to
"know" it. I could add a third and it would be more of the
same -- too much for my meager skills).  I could put on a
pair of NOs and get equallly even coverage and the plant
growth would would be nearly the same as with the 2 55w
PCs. This makes me think mere coverage isn't as useful rule
of thumb.

As for Amano, heckm I wouldn't expect to do as well as
Amano at 7 wpg (or much of anything else he does with
aquatic gardening :-\  )

I'd agree about 2wpg -- I'd call 2 wpg *low* light. George
thinks it's plenty, but I'm pretty sure he's referring to
PCs with really good reflectors and not, what did he call
them, "sucky bulbs".

Generally, an important thing to remember is that it's not
a situation where there is some right or wrong amount of
light (within a really broad range). And it's certainly not
a case of more is better, less is worse, or vice versa.
Down at one end you tend to have slow growth and are more
limited in plant selection and have less maintenance. At
the other end, things are just the opposite. If you want to
know where you setup is likely to come out in terms of
plant growth and maintnenance, wpg works pretty well (don't
know about the coverage rule yet) and it's much handier
than those other measures that would be better if they were
at hand.

George and I seem to disagree about the maximum approriate
amount of light. Obviously, 7 wpg can be made to work, if
that's where you want to go -- so I wouldn't call it
inappropriate. But maybe George doesn't want to hang a lot
on that one word "inapproriate." Maybe he just meant 3 wpg
is a whole lot. I'd still disagree; I don't think it's a
*whole* lot. But it's a smaller disagreement.

But then you all have to keep in mind, George and Karla
grow some beautiful tanks.

Scott H.

=====
S. Hieber

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