Lighting and Algae Control

Subject: Re: How long are lights good for?


George writes:

> >Perhaps the engineering charts don't take into account the fact
> >we turn our lights on and off each day (this shortens the life)

Greg writes:
> The engineering charts would be for typical use. Offices, shops,
> would turn their lights on and off every day.

In "Philips Lighting, Guide to Fluorescent Lamps" There is a graph 
that shows average life for a variety of different fluorescents 
based on burn hours per start.  You get almost double the life 
expectancy (in thousands of hours) out of a bulb with a 12 hour 
burn cycle as one with a 4 hour burn cycle.  (This would argue 
against the practice of an afternoon "rest" period in terms of 
lighting cost!)

The following is a quote from the same text:

"Longest lamp life and BEST LUMEN MAINTENANCE (emphasis mine) will 
be obtained with 1) good voltage, 2) proper auxiliaries, and 30 
favorable operating conditions such as are ordinarily encountered 
in a well-designed lighting system.  If in any installation the 
number of lamp failures wxceeds the theoretical number which 
should fail according to the formula:

# of failures    [hours burned/yr] [# of lamps]
               = _______________________________
    per year        Rated lamp life in hours

and this excess persists for an appreciable length of time, it 
would be well to look for some unfavorable condition in the 
installation or the method of operation which is adversely 
affecting lamp life."

I don't know whether the way we operate our lights would be 
considered "adverse conditions" or not.  Anybody know?


> Subject: Re: algae control

> >From: "Christopher L. Weeks" <c576653 at cclabs_missouri.edu>
> >Date: Fri, 10 Nov 1995 10:16:33 -0600 (CST)
> >Subject: Re: bacopa v's algae

> >Karen suggested that 

>   >"the 55g is underplanted and allowing the algae to bloom.  
>   >"Fill the puppy with plants and vary the lighting only if you
>   >to for the particular plants you select.   
>   >          
>   >Anyone agree or disagree?" 

No I didn't.<g>  That _could_ be the problem, but 1. I didn't 
respond to this post, and 2. I don't remember that Christopher 
told us how densely (or with what types of plants) his tank was 
> While I do not necessarily disagree, I do not think this approac
> usually reduce the stubborn kinds of algae that Christopher has.
> eliminating some needed nutrients from the water column by addin
> plants or accelerating their growth with more light and CO2 can 
> reduce algae. The varieties mentioned, however, tend to be more 

The reason I _didn't respond to the post is that I've seen people 
really struggle with this type of algae for long periods of time. 
I haven't heard a sure-fire fix for the problem, but it _does_ 
seem to go away if people are persistent enough and diligent 
enough. (Or maybe it would go away eventually anyway!<VBG>)

> BTW, does anyone know what aquarium book, if any, uses the term 
> algae. I assume this is the branching Pithophora.

George's book does.<g>  I don't off hand remember seeing it 
elsewhere, but I haven't looked for it either.

Karen Randall
Aquatic Gardeners Assoc.
Boston, MA