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Re: Perfecto Power Compact, Osram CF 55 watt

Michael Hennessey wrote:

>I just installed two Dupla electralights.  They each have two 55W CF tubes.
>It seems we can get all (or most of) the Dupla stuff in Australia even if
>its imported from Germany at a price that makes us cringe a little.
>
>The tubes that I now have seem a little yellow compared to the normal
floresent grower lights I have been using on my fish only tanks.  I was
>wordering if anyone had any experience with or details on my current tubes
>such as what is their K rating.  They are Osram Dulux L 2G11, 55W/21-840
>4800 Lumen Lumilux Hellweiss Cool Whites Made in Italy

Jim wrote:

>I am very new to growing aquatic plants.  Recently, I saw a 48" 55 watt, 4
>bulb full PC hood made by Perfecto for $219 -- bulbs included (My local
>pet store sells them).  It is not a retro-fit.  What I am wondering is why
>this brand of PC is so cheap?  I have seen PCs with the same specs for
>$500 or so.  Has anyone had any experience with this brand of PC?

I think I can shed some ligth (pun intended) on both questions:

Answering Jim's question first: the 48" Perfecto ShoLight has not 4 bulbs
but two 55 watt PCs. I have a 36" unit which also has the same two 55 watt 
PCs. It differs from the 48" only in size and the fact that the bulbs are 
mounted in staggered form. IMO it is cheap because, despite the electronic 
components being high quality, the assembly and quality control is shoddy. 
Mine came with the ballast loose and rattling inside the hood, and a loose 
screw felt from the box as I opened it (it came by mail from Pet Warehouse). 
I had to open the unit and put the screw back in place. The plastic hood 
is slim and the unit has to be handled with some care otherwise it seems 
its going to break apart. Despite of these problems, I'm happy with mine, 
it was a quick and relatively inexpensive way to bump my tank from 2 to 3 
watt/gal. It delivers a lot of light and less heat than the double 
(2 X 30 watt) fluorescent strip it replaced. 

A even cheaper way to upgrade the light strip would be to retrofit two 55 
watt kits from AH Supply. I couldn't figure how to stagger them inside the
narrow hood though.

Now to Michael's question: your bulbs are 4100K, 82 CRI. This is what
the "840" means. Let me report my experience with similar bulbs. My ShoLight 
came with two different PC bulbs. Both bulb packages list the color 
temperature as 5400K, as I ordered. But one package contained a Osram 
Dulux L 55w/12-950 bulb made in Italy, the other a SLI CF-L 55w/860 bulb 
made in Germany. The first is a 5400K, 91 CRI, 3800 lumen bulb. The second 
is 6500K, 82 CRI, 4800 lumen. So Perfecto's definition of "5400K" seems to be 
a bit vague. It turned out to be a good opportunity to put two similar bulbs 
side by side and see how these differences in specs translate to differences 
in perceived performance. The 6500K bulb looks noticeably brighter and bluer 
than the Dulux, as expected. The fish colors are noticeably washed out when 
compared with the higher CRI Dulux though. Fish with subtle iridescent
patterns such as male pearl gouramis look very different under each light.

Most of the difference in brightness between these two bulbs is in *perceived* 
brightness (lumens), not total PAR emission. The difference in PAR emission of  
these two bulbs is less than 10%, so I would give a preference for the Dulux
because of its higher CRI.

Regarding Michael's Dupla light, based on the bulb specs I would say that 
Dupla's design emphasizes perceived brightness in favor of color rendering.   

-Ivo Busko
 Baltimore, MD