# CO2 near empty



## aniroc (Aug 23, 2012)

I just noticed a drop in pressure (from a normal 900 to about 700 psi) in my single stage Smith regulator. Output pressure holds at 40 psi, running on solenoid for 5 hours a day. Obviously is time for a refill but I cannot do it sooner than 2 weeks.
Problem is: drop checker is yellow all the time (not very reliable in my case because actual CO2 bubbles can enter the airspace) and fish are a bit sluggish but not gasping at the surface.
Today I did a water change and removed half of the frogbit that totally covered the surface and things look better.
Should I continue to run CO2 and monitor it daily or should I turn it off and leave the tank without CO2 for 2 weeks? 
Is it possible for the solenoid to fail along the regulator during "dump"? How about the needle valve?


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## tom g (Jul 8, 2009)

*co2 fill*

Your tank wont suffer from lack of c02... in my case it didnt anyway.
what i used to do was have my tank on a scale .. measure before fill and 
after fill .gave me a better idea tank was getting empty..i dont thinkit will afect your tank 
so if u are worried about a end of tank dump.. that should take it out of your 
Mind...


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## hendy8888 (Sep 10, 2010)

I don't know about end of tank dump since I run a dual stage reg but once the pressure starts to drop I seem to get 4-5 weeks of co2 before its zero. The bubbles are too fast to count so it's going at a good rate. I have no experience when the tank would dump on a single stage reg though.


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## aniroc (Aug 23, 2012)

Thank you all. I unplugged the solenoid.
Just un update:
For a day, I thought my excess CO2 was because of the frogbit totally covering the water surface (preventing CO2 loss while blocking light to reach rooted plants).
CO2 stops at 1PM and lights go off at 6PM.
At 10PM last night I decided to check the water: pH was 6 (or lower as this is the lowest on the chart), KH was also 6 (6 drops with API test). According to KH/pH chart, the CO2 level should have been around 170ppm. I also took a tank water sample and left it in a cup: pH measured after 24 hours: 7.6 or higher (totally blue), confirming CO2 was outgassed.
Is it possible for fish to survive that high CO2 level?


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## tom g (Jul 8, 2009)

*co2*

How r your fish now.if they are struggling to breathe or u are
concerned shut co2 off and throw in a air bubbler to help dissipate 
the co2. ..


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## aniroc (Aug 23, 2012)

All fish (6 angelfish and 5 SAE's) are fine.
I stopped CO2 injection 2 days ago and they are much more active now.
But I am surprised how they survived the massive overdose: CO2 level must have been even higher at 1PM (when injection normally stops) then 9 hours later when I measure it that day.
I am wondering what limit can they tolerate? Most people will tell you:35-40 ppm. I know now that it is much higher.


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