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Re: Lighting, MH vs. Florescent

Karen wrote:
> > +  How long do MH bulbs last?
> > +  How many would I need?
> > +  How much do the bulbs and ballasts cost (ballpark)?
> 
> >From a cost perspective,  purchase price, replacement cost and 
> running cost, the cheapest good lighting is T-8's.  I have 6 bulbs 
> over my 70G tank, my replacement cost is $30 annually, they 
> consume 180W, and are at least as bright as Vitalites; bright 
> enough that my R. macrandra stays densely packed and incredibly 
> bright.  The bottom is entirely carpeted with Lillaeopsis, which 
> is another light hungry plant.
> 
> You can get _more_ light over the tank with MH's, but not 
> cheaper!<g>
> 
> The Degrees Kelvin is an indication of the strongest PEAK of light 
> in the bulb.  5500K is close to sunlight.

Gee Karen, I'll have to quibble with your statement that FL is 
cheaper than MH. I think it is cheaper when you're talking about
say ~100 watts or less but if you're up around 200+ watts, then
I think MH is gonna win the contest. You didn't quote an initial
cost for a 6 or 8 bulb t-8 setup including a hood either suspended
or sitting on top. My cost for each of my 250w MH pendants was
125$Cdn and replacement bulbs are $25Cdn. The bulbs decline in
output so if I really needed peak output, I could replace the
bulbs every year so my yearly cost is gonna be less than $25.
Of course, we're neglecting the cost of electricity and thus
we have to factor in efficiency. If I recall, the t-8s were
initially slightly more efficient than MH but during a 1 year 
rated life, I think the MH has a better efficiency. Experts 
please correct any inaccuracies (gently ;-). To determine the
optimal replacement cycle, we have to know the cost of electricity
and how much we can let the intensity drop before things go
wrong in the tank. One thing about FL, is you can maintain
a nearly continuous lighting level just by rotating the bulbs
through your replacement schedule. (write the dates on the bulbs?)

Anway, the costs work out close enough that I think it's going
to work out to a matter of preference since 10-20 bucks a year
isn't going to matter much to folks. We also have to stipulate
that there is a big difference between T-8s w high efficiency
ballasts vs. conventional cool-whites and off the shelf ballasts.

Anyway, if you're like me, some how the electricity cost doesn't
hurt as much as the pocket book cost of setup, or the maintenance
cost of bulky hoods vs. pendants or suspended hoods and the
postive results of higher lighting in the tank creating lusher
growth, and more varieties of plants. That's subjective. :-)

die-hard      an MH user, hooked on lumens (psst, Buddy!!
              try this; you'll LIKE it!!)