Re: Aquatic Plants Digest V2 #261

> ------------------------------
> From: JDAVIS at bio_tamu.edu
> Date: Wed, 16 Oct 1996 21:35:00 -0600
> Subject: DIY Chillers
> I have made a chiller for a reef tank that i kept a few years back.  The
 I took a "bar
> refrigerator" or a large dorm refrigerator and drilled two holes in the
> side of it.  Through the holes I fitted a threaded PVC bulkhead and to
> both sides I fitted hose barbs.  I ran about 25 feet of plastic tubing
> (figuring that there would be no worry about leaching any nasty
> chemicals from the hoses as opposed to using copper pipe with would have
> been a better conductor of heat) through the interior of the 'frige.  I
> turned the thermostat all of the way up (or is it down) and made the
> frige as cold as possible.  Then i slowly ran water off of a valve on
> the return from the pump to the tank.  This water circulated through the
> frige and returned to the tank about 5 or 6 degrees cooler that the
> water in the sump of the wet/dry.  It wasn;t much cooling...but it was a
> little.  Now, if I would have used a
> freezer....hmmmmmmmmmmm..........One thing that you would want to
> consider is the cost advantages of running a chiller or just air
> conditioning that one room.
> John
  I would make a couple of suggestions which might improve the
efficiency of your cooler.  
  1)  Add a large container of water to the frige.  Bend a series of
coils in your tubing and immerse the coil in the water.  Running the
water through this coil will increase the heat transfer immensely by
increasing the transfer surface area, and by using a water/plastic/water
interface Vs air/plastic/water.  
  2  Use metal if possible for the coil.  Plastic's heat transfer
ability is poor.  Aluminum would be ideal.  Copper is questionable, but
the pH and hardness of the water in your case may negate the problem. 
As I recall, the higher the pH (over 7.0), the more difficult it is for
the copper to stay in solution.  I believe the copper precipitates out,
but I'm not sure if the precipitate would be available to plants.  If
so, forget copper.  Any chemists out there with info on this? 
Availability of various metal tubing is an unknown to me, but I would
start with radiator shops or refrigeration repair services.  They may
even have something already available which would be suitable.  A third
source might be available through salt-water enthusiasts.  Cu is a big
concern with them.
  Good luck to all of you water coolers.  Let us all know of your
successes, There is no telling when we may need the technology for our
next 'hobby urge'.