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Re: CO2 regulators

> Date: Fri, 8 Sep 2000 12:09:03 EDT
> From: Dgrim62 at cs_com
> Also, IME, a pH probe will not suddenly "fail." What 
> I see initially are slightly abnormal readings brought about by a small drift 
> in the probe accuracy, and ending with a probe's inability to maintain 
> constant readings after a calibration. This happens over time and I have 
> always been able to tell far in advance when a probe was going to need 
> replacing. It is just normal maintenance to check the regulator gauge 
> readings, the bubble counter, and the Ph readings on your meter regularly 
> (every 2-3 days for me).  

Yes, I agree with all you said except that we DID see a probe suddenly fail. We 
monitor probe accuracy with a LaMotte narrow range pH kit and recalibrate when 
needed. We check at least every two weeks at water change time. 

When we had the failure, the meter was happily reading "7.1". Since the set 
point was 7.0, it was eagerly letting the CO2 run to bring the pH back down. 
When we caught it, the real pH was off the LaMotte scale (6.5) and looked to be 
below 6 using a cheesy Tetra pH kit. CO2 measured at 145 mg/l and the fish were 
either dead, dying or really unhappy. 

> A properly set up step down valve and needle valve on the regulator will not 
> flood the tank with excess CO2. 

It wasn't being flooded - it was working normally. But we are "cursed" with a 
very efficient Dupla reactor. Even with a slow CO2 flow, it will inject quite a 
bit of CO2.   

I don't see how our disaster could have beenn avoid except to go back to Lowe Tech. We never had a problem feeding CO2 into 
a canister filter. 

George Booth in Ft. Collins, Colorado (booth at frii_com)