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Re: Dennerle Lighting Recommendations

Mike Roberts wrote:
> 
> Subject: Dennerle Lighting Recommendations
> (snip)
> Nevertheless I found it interesting that the book advocates and sells Mercury
> Vapor Lamps as a high intensity "point" source of lighting.  After reading most
> of the archived Usenet articles on lighting on just didn't see many people
> advocating the use of these lamps.
> 
> Does anyone have practical experience with these lamps?  Are they suitable for
> use in a heavily planted freshwater tank?
> 

Mike, I recently switched from fluorescent lights to HQL. You have the Dupla
book so you can see that they also describe HQL (mercury vapor).
The tables show that it is less efficient than HQI (metale halides). 
But here in Germany HQI lights are awfully expensive so I chose HQL.

I bought two Duplalux HQL lights (you can see them in the book) 
switchable between 80 and 125 watts.
That is about 13500 lumens for my 60 gallons so should be more
than enough. The bulbs I use are Dennerle TROCAL HQL burners than give a very
good color renderition (sp?). TROCAL is a special Dennerle light color that
is supposed to prevent algae, a bit reddish. Also available as fluorescent
tubes.

Plant growth is getting faster now but I still have to fight some deficiences
(see my other posting on nitrate deficiency).

The Dupla lights have a very efficient gold-coated reflector (optimized for
depth) and are hanging 20 cm over the tank so that almost all light goes into 
the tank. They have an extra protection
glass so that you can put them close to the water surface without risking
to damage the bulb with accidential water splashes which they don't like... 
And yes, they are expensive as Dupla is never cheap :-( But the Dennerle lights
for example don't have the protection glass.

Here are some points I learned when comparing HQL and HQI. Based on this, I
went for HQL as my tank only has a water column of 40-45 cm.

HQL:
+ cheaper than HQI
+ nice effect when switched on - like a sunrise
+ switchable between 80 and 125 watts
o can be used for water columns up to 50-60 cm
o I am not too sure if HQL or HQI have the better light color but Dupla says 
   that intensity is more important than color
- cannot be used for salt water
- less efficient than HQI

HQI:
+ more efficient than HQL
+ can be used for salt water with different protection glass (and burners?)
o can be used for water columns up to 70-80 cm
- expensive (casing and burners)
- more UV light -> more algae (some stores stated this, I am not too sure if
   it's true)
- hotter than HQL (burning risk and costly casing)

Just my 2 cents...
No, I am not working for Dupla or Dennerle, I only like their products :-)

Greetings, Andi from Munich, Germany.