Re: Fluorex Lights

["Wayne J" <w.jones at sympatico_ca>]

Scot wrote:

That above quote is, well, technically accurate but not
quite realistic.  Some lumens are usable by some plants and
others are, depending on wave lengths, so even more data is
needed ;-)
-------------------------------------------------------------
It's perfectly realistic. I do it all the time to predict how much light a
fixture is likely to produce.  It's not difficult to do and doesn't require
much in the way of special knowledge. You don't have to be perfect about it
but you have to at least make a guess on the values.

Scott wrote:

Actually, what I want to remind folks is that it's
unrealistic for a bigger reason.  It's sort of like saying
you can't tell how much gas mileage a car will really get
unless you take samples and operate on the roads you
normally drive, in the ways you normally drive, do some
research on the gasoline, the engine, and a few other
things -- if you really want to know what the car will do.

----------------------------------------------------------------

It's not at all like that. Automobile manufacturers publish gas mileage just
like good fixture manufacturers publish LERs. The whole point of what I am
saying is that it is possible to predict light levels BEFORE you buy the
fixture. Once you have bought it you are stuck with it. I am pretty sure you
wouldn't buy a car without finding out the gas mileage before you bought.
and I am pretty sure you wouldn't buy a car just because someone told you it
got "great" gas mileage. You would want to know what "great" means
especially compared to other cars.

Scott wrote:

Most folks aren't
in positions to do new research nor find ballast factors,
quantified reflector assessment values, bulb lumen ratings
(especially those that your plants can use, and which are
set by established standards anyway) or even get
assessments of bulb lumen output generally, for specific
bulbs.
-----------------------------------------------------------------

You are confused. The lumens produced by a light fixture can be directly
compared as long as you use the same spectrum lamp. Which lamp you use is a
separate issue. Some have a little more plant usable light per watt than
others but on the whole it doesn't matter that much. As far as I can tell
the lamp spectrum of a fluorescent lamp might make a difference of plus or
minus 10% but it's probably less than that.

Scott wrote:

It would be nice if manufacturers used straightforward,
standardized ratings, but they don't.   And with
fluorescent bulbs, ratings can only work with specific bulb
and ballast combinations.  Although it wouldn't be too hard
for ballast manufacturers to include with a ballast a list
a standardized ratings for a wide variety of particular
bulbs (call your congresswoman or congressman).

-------------------------------------------------------------------

They do publish this stuff. It is mostly only aquarium specific equipment
that gets ignored and even then you can look it up or guess at most of it. A
wild guess at fixture efficiency and ballast factor is still far better than
the watts per gallon rule any day.

Scott wrote:

Wpg will get most folks pretty far,

-----------------------------------------

It just gets most people confused. Someone just asked about CFs on small
tanks. The 10 gallon tank requires 5 watts per gallon of CF the 20 gallon
tank requires 4 watts per gallon of CF. If you were to use a 40 watt AH
Supply kit at 2 watts per gallon it would be just a little bit less light
than 4 watts per gallon of CF. Watts per gallon sucks. It just makes people
jump to the wrong conclusions over and over and over again.

Scott wrote:

The deep data method is a good way to compare lamps if you
can do it.  But it's not necessarily the best way because
it not as practical as some of the other methods.  It's
certainly not a necessary method for successful gardening.

----------------------------------------------------------------------------

Certainly you can just accept what someone else says is the right amount of
light and if you listen to the right person they will be correct. The fact
is though that most people look at light levels in a very subjective way.
One man's high light is Tom Barrs low light ;-) Like I said before
calculating light levels using lumens is the only way to predict light
levels. This is a only really important when choosing a light fixture. Once
you actually have a fixture there is not much point in doing this. No one
has to actually do it if they don't feel like it. Just buy whatever fixture
you want plunk it over your tank and see if it's enough. If you don't like
it you can try something else. Of course this is the way my mechanic tries
to fix my car but it does get rather expensive.

Wayne