Re: Aquatic Plants Digest V1 #255

> From: olga at arts_ubc.ca
> Date: Wed, 14 Feb 1996 14:41:57 -0700
> Subject: White scum?
> Ok -- what's going on now? :(  Suddenly, I have a thin white film on the
> top of my tank, kinda like an oil slick. It looks thick and yucky when I
> look up at it but when I open the hood and look down on it I almost can't
> see it. If I stir it around it breaks up into pieces (like ice floes) but
> doesn't dissolve. What is this? Can I get rid of it? Does it have to do
> with adding more fertilizer lately?

Yes it does. What you are observing is "iron bacteria"  If you look 
closely it is actually bluish-grey film caused by iron consuming 
micro-organisms. This indicates sufficient iron present in the water.
This phenomena can be often observed in tropical streams where there 
is a large supply of bivalent iron leaching into the stream. It is 
not dangerous at all and will dissapear shortly on its own. 


> From: Gennady Galanter/jfrank <Gennady_Galanter at jfrank_COM>
> Date: 14 Feb 96 16:23:49 
> Subject: Using Fire Extinguisher Cylinder for CO2 Generator.
> I read a lot about using Welding cylinder as the container for CO2 generator.  
> Has any one tried using the fire extinguisher one for that purpose?  What is 
> wrong with using that?  I found one for $20 while those for welding run about 
> $50.
> Thanks.
> GG~|:-)'

I use fire extinguisher as my spare CO2 cylinder for several years 
now without any problems. It certainly meets all safety standards.
You should have it inspected however since it is not uncommon for 
such a cylinder to be in service for 30 years + . It could have 
started as "soda machine" cylinder where there was often a backflow 
of water  when the CO2 was exhausted and that created strong carbonic 
acid slowly dissolving the walls of the cylinder. I have a friend who
fills up my cylinders and have seen quite a few such ones. There is 
a requirement  for all CO2 cylinders to be inspected and weighed 
every so often(depends on a local code) , at least here in Canada.
There is a lot of pressure in those things so I'd be carefull.

Franc Gorenc                  franc at golden_net
Kitchener, Ontario          http://www.golden.net/~franc