GardenBanter.co.uk - View Single Post

09-11-2004, 03:35 AM

In article ,
says...
"Allan" wrote in message
news:MPG.1bf8a99e24d8b458989682@news-server...

I got a JBJ combo regulator, solenoid, needle valve, check valve, &
bubble counter in the mail on Monday and attached it to my 10 lb CO2
tank. The high pressure gage read 800 psi (is this the normal reading
for a full tank?).

Seems low. The pressure of liquid CO2 at room temperature (below 30C)
is 60bar, which is 870psi. Possibly, your tank wasn't fillled? Note that you
cannot use pressure to tell how full a CO2 tank is because the pressure stays
exactly at 60bar until the tank is almost empty and there is no more liquid
CO2 left. If you want to know whether you have a full tank, weigh it empty
and again after a refill.

I went and got a refill today. Pressure is similar (~830 or ~840 psi),
so I assume that is just an inaccuracy of my regulator.

I started bubbling at one bubble per second. and let it run through the
night. The next morning, my pH had not moved. I kept increasing the
bubble rate until it was going too fast for me to count (5 to 10 bubbles
per second!). After doing this a couple of days, my pH had only lowered
by 0.2 or 0.4 to around 7.2. The pressure on my tank had dropped by 300
psi so I scaled the bubble rate back to one per second. This morning, my
CO2 tank was flat empty.

I'm finding it impossible to believe that could have emptied out 10 pound tank
this quickly, unless you have a leak. So, first, check whether your tank was
actually full. (Given that you read 800psi instead of 870psi, I suspect you
may have started with a nearly empty tank.) Next, take a spray bottle, put
in a little bit of water and a few drops of detergent, and spray the the
various
parts of your system. You will see bubbles if you have a leak.

From a rough estimate, the previous tank felt a similar weight to this
one, so I'm pretty confident it was full. Anyway, I found the leak
tonight. The threaded portion of the needle valve that the bubble
counter attached to was the culprit. I wrapped some teflon tape around
it and it seems to have stopped the leak for now.

If you want to control the CO2 content to any degree of precision, an
ordinary indicator pH test is too coarse, IMO. At least, I can't tell the
difference between 6.6 and 6.9 with any real reliability, but that's a
big difference in terms of CO2 content (too much vs too little). A better
option is to get a electronic meter. These are precise to withing +- 0.01
degrees after calibration.

An AquaController II should be arriving tomorrow. I'll hopefully have
more concrete data then.

Thanks for the input.

-- Allan