Chuck,

Although I do have a needle valve, I believe it must be relatively low
quality. I bought it as part of a set offered by Ultra Life three years ago.
With my current needle valve, I could not expect anywhere near constant flow
as the tank pressure drops--- especially if it dropped to 50 PSI. Actually,
my needle valve is persnickety even as the temperature of my CO2 tank
varies. For example, when I attach in a refilled tank that is perhaps 20
degrees cooler than the room temperature, I can set the bubble flow
conservatively at a bubble count of one or two per second with the cool
tank, and by the time the tank warms up, there will be almost no flow
because, I presume, of the change in pressure. To deal with this, I have to
let the refilled tank sit at room temperature before connecting to my
system.

I am 6 or 8 months from setting up another large tank in my basement, so I
will take a look at the links on your site regarding where to purchase
needle valves at that time. (Thanks for all the good info on your web site,
by the way. Its always a tremendous resource for me.)

I do like having a controller attached, since it constantly displays the PH.
After breaking in my controller probe, I have never in three years seen the
calibration move more than .03 PH points. And this large of a movement is
associated with testing at the PH=4.0 level. This means the error in the
range of interest, much nearer to neutral 7.0 PH, is very small indeed. The
error in the 7.0 range has never exceeded .01 PH points (after the probe is
broken in). A new probe requires a couple of calibrations a week or two
apart, when there may be more drift in the calibration as the probe is
"broken in".

For what its worth, I have very much found that a controller is a
set-it-and-forget-it type device.

-Bruce
http://www.wideopenwest.com/~brucegeist

"Chuck Gadd" wrote in message
...
On Sun, 28 Sep 2003 00:54:37 -0400, "Bruce Geist"
wrote:

I have run a pinpoint controller for some years now, and am very happy
with
it. It works beautifully, and keeps my tank PH rock steady even when
the
CO2 tank begins to dump (as it runs out of pressure).

A needle-valve by itself will do the same thing. I finally changed
out my 10lb tank this week. The pressure started dropping more than a
month ago, and by the time I got it swapped out, the tank pressure was
down to less than 50 psi. It was the furthest I've ever pushed
things, and the tank never did dump.

This is with the inexpensive "Dave Gomberg" beer regulator.


Chuck Gadd
http://www.csd.net/~cgadd/aqua