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Re: Best fluorescent tubes? / ahsupply.com

Jason said, in part:

> When looking at http://www.ahsupply.com, I notice the
> bulb lengths are not
> in the standard 24", 36", etc.  I take it 21.1" = 24"? 
> And 34.1" = 36"?
> Kind of confusing.  My bulbs were sold as 24".  So I am
> assuming I cannot
> use these bulbs in my standard ballast? . . .

Short answer is, stepping up in a practical way to more
light means a different kind of bulb and ballast or more
bulbs and ballasts.  Your hoods can use 2 standard 2 foot
bulbs.  Actually, the ballasts in them are probably
intended to run standard bulbs that are rated anywhere from
15, 18, to 20 watts -- it probably says so right on the
ballasts.  They overdrives the smaller ones and underdrive
the larger ones.  You see, although ballasts must match the
bulbs, the fit doesn't have to be too close.  But a
standard flouresecent ballast won't drive PCs or VHOs. 
Some bulbs are brighter than others but you won't see a lot
of difference in useful light output from one bulb to the
next -- pick any triphosphor bulb that looks nice to your

The longer answer follows.  Plant lighting can seem a bit
confusing so maybe this (over)generalized primer will help.

There are several kinds of fluorescent lamps.  Each type of
fluoresecent lamp, genrally speaking needs a ballast that
is matched to it -- the closeness of the match is another
story.  The ballast controls how much current a bulb gets
-- a fluorescent, once lit, will take all the current you
give it until it "flames out."  It needs the ballast to
limit the current.  It also needs the ballast to convert
your household 110-120 Volts to something high enough to
arc from one end of the bulb to the other.  Different
ballasts have different effects on current and voltage.  

Standard fluorescents (Or Normal Out or NO) -- you see all
over the place and in office buildings

High Output Fluorescents (or HO) -- these are not often
used because there are better options -- these are just
like standard fluorescents but they are built to withstand
being driven by a ballast the runs more current through

Very High Output (or VHO) -- these are like HOs except made
to withstand even higher wattages.  They come in the same
sizes as standard fluorescents but need ballasts intended
to drive VHOs.  Sometimes NO bulbs will light on these
ballast and burn very bright, but hey burn out quickly.

Power Compact (or PC) -- these are a kind of very high
output bulb that uses a smaller diameter bulb, better
phopsphors, and usually, and electronic high frequency
ballast to get more output from a given size.  There are
"standard" lengths for PCs.  The 55 watt bulb is just under
2 feet so, with a socket on it, it still fits in the space
of a 2 foot NO bulb (usually anyway).  The 96 watt bulbs
are jsut under 3 feet long and with socket will fit into a
3' space.  PCs need a ballast that's meant to drive them. 
Some VHO ballasts will light them and some PC ballasts will
light VHOs.

There is a variation on PCs often referred to as Compact
Fluorescent.  You see these for sale in Home Depot and
such.  the fit in a regular incandescent light socket and
the fluorescent tube is twisted into a spiral or several
short up and down lengths so the bulbs will more easily fit
into regular incandescent lamps.  These bulbs have their
ballast built right into the bulb.  The advantage of these
bulbs is that they can be found relatively cheap and they
can go right into your table lamp.  Problem is the twisting
of the tubes reduces the effective output because so much
of the light just leaves one tube to hit another.

Several companies sell ready-made Power Compact hoods. 
Same is true for VHO hoods.  They are expensive.  As an
alternative, many folks buy kits and make their own hoods
or rebuild their existing hoods.  AH Supply, imo, is one
the best places around for going this route.  Their
reflectors are the best, ballast are high quality, and
their prices are good and the staff are very helpful.

Some ballasts are more flexible than others.  Electronic
ballasts, depending on their specific design, can run
different amperages and voltages on different lamps.  How
this works is complicated but it's true.  Also, bulbs are
designed to operate within a range of voltages and amps
just so that they will operate on more than one specific
ballast.  For example, your 2 foot NO bulb is operating on
a ballast that's putting only about 18 watts into the bulb,
but it still works pretty good, right?  It would be a
little brighter running at a full 20 watts but it will last
a little longer running at 18. 

The ballasts that AH Supply sell can be used on a variety
of bulbs.   

BTW, AH Supply also sells ready made hoods and their
instructions for assembling their kits are very good --
easy to follow.

Within each of the categories of fluorescent lamps there is
a multitude of "types" to choose from where one is
supposedly better for plants, one is beter for kitchen
lighting, one better for baths, for coral -- it goes on and
on.  The main difference is the kind and quality of
phosphor paint on the inside of the bulbs, which affects
the wavelength of the light given off -- ie, the spectrum.

Cheap bulbs, the ones in most office building give off lots
give off green light, which most plants don't use; they
reflect it right back.  They use one simple cheap
halophosphate for a phosphor.  Triphosphor bulbs use more
kinds of phosphates, and give off more red, more blue, more
yellow light, depending on the mix of phosphors used.  Your
plants will pretty much "think" one triphosphor is as good
as the next but they will be rather concerned about the

Scott H.

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