Re: Bubble counters?

["S. Hieber" <shieber at yahoo_com>]

Thomas Barr asked:<tcbiii at earthlink_net>
> 
> My question is more along the lines of why does ANYONE need a bubble
> counter
> in the first place? We focus on the pH for precise CO2 determination,
> not
> bubbles per sec. All it shows is some flow is going into the system,
> not
> that much more. 

That's just about it for me.  Once I get a tank reasonably stable, I
know about what bubble rate gives me the CO2 level I want.  Also, I
don't measure a stable tank as often.  In between, a glance at the
bubble counter tells me readily if the rate has gone substantially
higher or lower.  Three things can give me an at-a-glance indication of
CO2 levels:  The water level in the reactor, the low-side regulator
pressure reading, and the bubble count.  A bubble counter gives me a
slightly better estimate than just looking at the gas space at the top
of the reactor or the pressure on the output side of the regulator.  If
it looks too slow or fast, then I might count the bubbles or just test
the water.

I am usually reminded to check for a CO2 tank that is getting low by a
noticeable speed-up in the bubble rate.  On my regulators, that's a
good indication that the high side pressure is dropping down below 600
or so, causing the low side pressure to rise.

So, for me, it's just an extravagant convenience -- like having an
electronic pH monitor when pH chemical tests only cost a few bucks per
year.  I could get by without one, but I don't have to.

With a piece of about 3/4 inch clear rigid tubing, some rigid airline
tubing and some aquarium-safe silicone sealant you can make a bubble
counter in a minute or two.  Cut big tube to about 4 inches long,
insert small diameter tubing about 1 inch into the big tube on each
end.  Gob the ends of the big tube with the sealant nearly filling all
the way  to the ends of the small tube.  Let sealant cure for 12-24
hr.s. [Okay, the curing time makes this project take more than a few
minutes, but you can do other stuff while the sealant is curing ;-)
]Attach a check valve to one end and treat that as the bottom.  Fill
3/4 full with water. Put in-line on your CO2 tubing.  With a little
imagination, you can fancy that up with end caps (bottle caps or PVC
end caps) if you run relatively high pressure into you
reactor/diffuser/etc.  Or you can add Christmas tree lights, whatever
you like.  If you are worried about relatively high pressures
generating a leak, then use Epoxy (very carefully) instead of silicone.

Scott H.

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