I'd be concerned about leaving even a moderately strong chlorine solution 
in the system for even a few days.  Chlorine is extremely corrosive to 
many metals - even stainless steel.  Better, I think, to hit it with a 
dash of bleach, pump some through the piping, and drain it.  Also, 
chlorine bleach is not, in itself, an effective cleaner.  Indeed, it's 
disinfecting action is blocked by accumulations of organic matter, such 
as algae.  

As an alternative (though I haven't tried it), one might use one of the 
commercial iodine based cleaner/disinfectants known as iodophors that are 
used in the restaurant/bar trade for cleaning glasses.  Iodine is very 
similar to chlorine in its sanitizing properties, but has the advantage 
of being non-corrosive.  It also does not dissipate into the atmosphere 
like chlorine, retaining its effectiveness longer.  I'll try to check it 
out further - I know a company that manufactures these kind of products 
for the food and brewing industry - and try to get a better read on it.  

--------------------------------------------
Wes Neuenschwander
Seattle, WA

(wesn@eskimo.com)