I have a rainwater system at my get away in the Gulf Islands and have the
same questions. There is enough carbonic and sulfuric acid in the rain to
use ss rods but if you want to obtain a sort of gas gauge here's the
ticket: a plastic tube containing reed switches connected to a resistor
ladder then to a pin on your pic. the tube is sealed on both ends with the
wires out of one end. then a large cork fitted with a magnet is drilled and
fitted captive on the tube. epoxy coat the float and this set-up will last
for years.

Good Luck

Wil Reeder
Vancouver, Canada

----------
> From: Clyde Smith-Stubbs <clyde@HTSOFT.COM>
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: Sensor questions (maybe [OT])
> Date: Wednesday, April 08, 1998 11:59 PM
>
> On Wed, Apr 08, 1998 at 09:35:31PM -0500, RICHARD SKINNER wrote:
> > I understand the concept of air being dissolved into the water, "but",
We
> > run that setup on locations
> > everywhere, with ss tubing ran to a "Wc Sensor,  We have no ill effects
what
> > so ever.  Now granted, we
>
> How often is the bottom of the tube uncovered? This approach is certainly
one of
> the most convenient from the mechanical point of view, particularly as
the tube
>  could
> be run some distance back to a more convenient location for the
electronics.
>  Which
> would also make it more feasible to hook in an air pump (the common fish
tank
> pumps require mains supply since they're just mains frequency vibrators).
>
> Incidentally, the excellent response to this question probably justifies
more of
> an explanation of the application. I recently moved to a new house which
has no
> town water and relies on rainwater for household use (so did my old
house, but
> its single tank had a readily accessible manhole to inspect the
contents).
>
> There are two tanks, each about 7000 gallons (imperial); the main tank is
filled
> from the house roof, and water is drawn from it with a pressure pump. The
other
>  tank
> is filled from the garage roof, and also overflow from the main tank,
which is
>  about
> 2m higher. I just had a pump fitted to allow water to be transferred from
the
> lower tank to the main one. The level sensing is mainly to know when the
top
> tank is getting low, so the pump can be turned on refill it. It's also
handy to
> know when you're about to run out of water (in the middle of a shower is
not
> a great time) - in dry times it may be necessary to get water trucked in.
>
> Once the level sensing is working ok, I will probably rig it to turn the
>  transfer
> pump off once the tanks reach certain levels, but will probably leave the
pump
> activation as a manual operation.
>
> Of course this could probably be done just by calling a professional, but
then
> I wouldn't learn anything :-)
>
> Cheers, Clyde
>
> --
> Clyde Smith-Stubbs               |            HI-TECH Software
> Email: clyde@htsoft.com          |          Phone            Fax
> WWW:   http://www.htsoft.com/    | USA: (408) 490 2885  (408) 490 2885
> PGP:   finger clyde@htsoft.com   | AUS: +61 7 3354 2411 +61 7 3354 2422
>
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