why is my bubble rate changing?

[Matt Hanson]

I've had a very bad problem over the last few days with my brand new
high pressure CO2 setup. (not DIY!)

I cannot keep a constant bubble going for more than a few days at a
time. Here are the factors that I have eliminated:

1) not too long of a length of tubing, to or from anything. Shorter
tubing would eliminate any kind of pressure hold. Additionally, I ran a
very short length of the larger diameter line, for this very reason.

2) constant temperatrue - not sure if even a change of 20 degrees would
have much effect, but nonetheless, it's not a problem.

3) no leaks - I bubble tested with soapy water.

4) not a regulator or valve disturbance - very sure.


So then, I have checked these things, and found nothing to be out of the
ordinary. Yet, one day I have 1.5 bubbles per second, the next day,
about 1 bubble every 10 seconds.

Does anybody else have this kind of experience?

BTW - for what it's worth, I have one of those "needle valves" from Home
Depot. I'm already starting to suspect the problem might be somewhere
there. It's not even really a needle valve, so the control is less than
desireable. I'm not quite sure how they can even be marketed as a
needle valve. Tell me folks, is it in the valve?

[Scott Rogahn]

My bubble rate takes some time to become stable. The key is to make small
adjustments and check after a long settling time.
Like you I am using a cheap needle valve from a local hardware store.
When this valve is completely closed I can get about 45 bubbles per minute
if I adjust the pressure to ~4 pounds. If I crack the valve just a fraction
of turn the bubble rate goes way up. So for me it is best to leave it
'closed' and adjust my rate by pressure. I will make 1/2 to 1/4 turn at the
presure regulator and check after a hour or so. After a few tweeks over a
couple of days every thing remains stable. Leaving the needle valve alone
and adusting presure may go againt convetion wisdom, but it works for me.

Scott


"Matt Hanson" > wrote in message
...
> I've had a very bad problem over the last few days with my brand new
> high pressure CO2 setup. (not DIY!)
>
> I cannot keep a constant bubble going for more than a few days at a
> time. Here are the factors that I have eliminated:
>
> 1) not too long of a length of tubing, to or from anything. Shorter
> tubing would eliminate any kind of pressure hold. Additionally, I ran a
> very short length of the larger diameter line, for this very reason.
>
> 2) constant temperatrue - not sure if even a change of 20 degrees would
> have much effect, but nonetheless, it's not a problem.
>
> 3) no leaks - I bubble tested with soapy water.
>
> 4) not a regulator or valve disturbance - very sure.
>
>
> So then, I have checked these things, and found nothing to be out of the
> ordinary. Yet, one day I have 1.5 bubbles per second, the next day,
> about 1 bubble every 10 seconds.
>
> Does anybody else have this kind of experience?
>
> BTW - for what it's worth, I have one of those "needle valves" from Home
> Depot. I'm already starting to suspect the problem might be somewhere
> there. It's not even really a needle valve, so the control is less than
> desireable. I'm not quite sure how they can even be marketed as a
> needle valve. Tell me folks, is it in the valve?
>

[Bob Alston]

If you ever want to consider something a notch better, the Clippard needle
valve, MNV-4k2, is widely used for high pressure aquarium CO2 and can be
obtained from a Clippard distributor, if there is one in your city - check
www.clippard.com - for $10.10 If no local Clippard distributor, you can get
it from M3, Aquabotanic, florida Driftwood and likely others for 20-25$ plus
shipping. Better than your "cheapo" but not great.

To learn more about needle valves, maybe more than you ever wanted to know,
take a look at my web site:

http://members.cox.net/tulsaalstons/AquaticPlants.htm#High%20Pressure%20CO2

Look at item #3 - CO2 needle/metering valves

--
Bob Alston

http://members.cox.net/tulsaalstons/
"Scott Rogahn" > wrote in message
...
> My bubble rate takes some time to become stable. The key is to make small
> adjustments and check after a long settling time.
> Like you I am using a cheap needle valve from a local hardware store.
> When this valve is completely closed I can get about 45 bubbles per minute
> if I adjust the pressure to ~4 pounds. If I crack the valve just a
fraction
> of turn the bubble rate goes way up. So for me it is best to leave it
> 'closed' and adjust my rate by pressure. I will make 1/2 to 1/4 turn at
the
> presure regulator and check after a hour or so. After a few tweeks over a
> couple of days every thing remains stable. Leaving the needle valve alone
> and adusting presure may go againt convetion wisdom, but it works for me.
>
> Scott
>
>
> "Matt Hanson" > wrote in message
> ...
> > I've had a very bad problem over the last few days with my brand new
> > high pressure CO2 setup. (not DIY!)
> >
> > I cannot keep a constant bubble going for more than a few days at a
> > time. Here are the factors that I have eliminated:
> >
> > 1) not too long of a length of tubing, to or from anything. Shorter
> > tubing would eliminate any kind of pressure hold. Additionally, I ran a
> > very short length of the larger diameter line, for this very reason.
> >
> > 2) constant temperatrue - not sure if even a change of 20 degrees would
> > have much effect, but nonetheless, it's not a problem.
> >
> > 3) no leaks - I bubble tested with soapy water.
> >
> > 4) not a regulator or valve disturbance - very sure.
> >
> >
> > So then, I have checked these things, and found nothing to be out of the
> > ordinary. Yet, one day I have 1.5 bubbles per second, the next day,
> > about 1 bubble every 10 seconds.
> >
> > Does anybody else have this kind of experience?
> >
> > BTW - for what it's worth, I have one of those "needle valves" from Home
> > Depot. I'm already starting to suspect the problem might be somewhere
> > there. It's not even really a needle valve, so the control is less than
> > desireable. I'm not quite sure how they can even be marketed as a
> > needle valve. Tell me folks, is it in the valve?
> >
>
>

[Dave Millman]

Scott Rogahn wrote:

> My bubble rate takes some time to become stable. The key is to make small
> adjustments and check after a long settling time.
> Like you I am using a cheap needle valve from a local hardware store.
> When this valve is completely closed I can get about 45 bubbles per minute
> if I adjust the pressure to ~4 pounds. If I crack the valve just a fraction
> of turn the bubble rate goes way up. So for me it is best to leave it
> 'closed' and adjust my rate by pressure. I will make 1/2 to 1/4 turn at the
> presure regulator and check after a hour or so. After a few tweeks over a
> couple of days every thing remains stable. Leaving the needle valve alone
> and adusting presure may go againt convetion wisdom, but it works for me.

Scott,

It doesn't sound like your needle valve is much of a valve!

[Dave Millman]

Matt Hanson wrote:

> I've had a very bad problem over the last few days with my brand new
> high pressure CO2 setup. (not DIY!)
>
> I cannot keep a constant bubble going for more than a few days at a
> time. Here are the factors that I have eliminated:
>
> (snip)
> BTW - for what it's worth, I have one of those "needle valves" from Home
> Depot. I'm already starting to suspect the problem might be somewhere
> there. It's not even really a needle valve, so the control is less than
> desireable. I'm not quite sure how they can even be marketed as a
> needle valve. Tell me folks, is it in the valve?

Your suspicion is correct!

[Aqua]

"> BTW - for what it's worth, I have one of those "needle valves" from Home
> Depot. I'm already starting to suspect the problem might be somewhere
> there. It's not even really a needle valve, so the control is less than
> desireable. I'm not quite sure how they can even be marketed as a
> needle valve. Tell me folks, is it in the valve?

If you are using any check valve, that could be the problem too.

I am using the same "cheapo" home depot needle valve for the past one year
and my 5 lb. tank is coming around 6 to 7 months. My output pressure is 15 -
20 psi. Currently I have 80 bubbles per minute. I would suggest you to
tighten the top "nut" (the one below the 'T') if you really suspect the HD
needle valve.

Post your findings.

--
Thank You

Dominic
http://www.dlink.org/aqua