Re: metal halide, mid day dark per.

On Wed, 2 Aug 1995 Aquatic-Plants-Owner at actwin_com wrote:

> From: mleather at tbdmil_com
> Date: Wed, 02 Aug 95 08:59:16 -0600
> Subject: metal hide
>         Well i was suggested using a 100 watt mh bulb for my 29 gallon
> tank.  Off hand it sounds like a it is a bit powerfull but I'm open to
> the possibility.  Question is are there hoods or lights readily available
> in metal hide or is it a custom build it your self project.  Also what
> dennis

It seems to me that George Booths recent definitions of "enthusiast" vs. 
"fanatic" are applicable here.  I don't know much about metal halide, but 
you can grow a great variety of plants with a $7 shop light, and a few 
good flourscent bulbs--in my experience at least one should be a 
tri-chrome type.  If money is no object, give the metal halide a try.  
But if you're on a budget like I am, and are an "enthusiast" without the 
funds to be a "fanatic", you can  have a lot of fun and still pay the bills 
with fluorescent lights.

> ------------------------------
> From: "John Y. Ching" <jyching at watnow_uwaterloo.ca>
> Date: Wed, 2 Aug 1995 11:13:29 -0400 (EDT)
> Subject: Additional lighting caused algae bloom?
> I just remembered that the algae proliferation I described earlier
> also coincided with my adding of two additional fluorescent lights
> (2x40w), making it a total of 6x40w (2 tritons, 2 ultralume daylight,
> 2 cool whites). It is possible that my plants failed to compete 
> successfully against the algae for the additional lighting. Hopefully
> the new CO2 tank plus needle valve control would provide more 
> consistent CO2 fertilization and allow the plants to out compete the 
> algae. I also implemented an 2 hour dark period at midday each day, and 
> a complete dark day on Wed of each week, following some suggestions in
> the archives.
> Thanks for listening.
>  John Y. Ching (jyching at watnow_uwaterloo.ca)    |
>  Pattern Analysis and Machine Intelligence Lab	| 
>  Department of Systems Design Engineering      	| 
>  University of Waterloo, Canada            	| 

I would like to see some data on the midday lights-off regime.  I have no 
biochemical data to contribute, but my observations of the leaf movements 
of some aquatic species don't seem to support the notion of a midday rest 
period.  Two plants which I have good success with, Rotala indica and 
Hygophila poylsperma, have distinct leaf patterns.  Early in the morning, 
the top leaves are perpendicular to the light source.  Around 7-8AM they 
become parallel to the light source to intercept it.  Around 12 
hours later, the top leaves begin to fold perpedicular again.  If one 
kills the lights at midday, when at least morphologically the plants are 
in high gear photosynthentically (again, no biochem. data), one can't 
"make up for lost time" in the evening as the leaves seem to be shutting 
down for the night.  These types of rythyms (called circadian, 'about a 
day') are maintained independantly from environmental stimuli.

So if the goal is to out compete the algae, shutting off the lights at 
midday seems to put the plants at a competitive disadvantage.  This 
assumes that algae are always willing and able to photosynthesize, given 
adequate nutrients and light.  Have I missed something on this?  I find 
it an interesting thread.  

paul bucciaglia