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Thread: CO2 Shut Off After Time Limit Expires

  1. #1
    Frequent Visitor bigjim's Avatar
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    CO2 Shut Off After Time Limit Expires

    I use a PH probe to open and close the solenoid valve on the CO2 tank (located in the cabinet under my DT) that feeds my CA reactor. A friend of mine who is a first responder pointed out how dangerous this is (especially in the winter when the house is sealed up) and that I need to program the solenoid valve to automatically close (and turn off) after running a certain amount of time without the PH probe showing a drop in reactor PH. How do I do that? Also an email and SMS alert needs to be sent to me and my wife along with our emergency contact.

  2. #2
    Frequent Contributor zombie's Avatar
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    The amount of CO2 added from a calcium reactor is not dangerous particularly since it is dissolved into water and not released directly into the air. The pressures are very low and are roughly equivalent to a couple extra people in your house.

    With that said, it's still a good idea to limit how long it can run to prevent melting your media if the probe goes too far out of calibration or fails.

    The actual approach depends on how you want it to behave when that maximum time is reached. Do you want it to self reset and try again after a specified amount of time (if so what max time and wait length do you want), or do you want it to lock off until you manually reset it?

    Sent from my SM-G965U using Tapatalk

  3. #3
    Frequent Visitor bigjim's Avatar
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    The concern is the tubing disconnects or fails (evidently aquarium air tubing can fail due to prolonged CO2 exposure) and the entire 10 pound tank empties into the room.

    I would like to set a time limit the CO2 can run (say 2 minutes) and then set the solenoid to OFF so it would require manual intervention to set it back to AUTO.

  4. #4
    Frequent Contributor zombie's Avatar
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    Quote Originally Posted by bigjim View Post
    The concern is the tubing disconnects or fails (evidently aquarium air tubing can fail due to prolonged CO2 exposure) and the entire 10 pound tank empties into the room.

    I would like to set a time limit the CO2 can run (say 2 minutes) and then set the solenoid to OFF so it would require manual intervention to set it back to AUTO.
    Your primary regulator protects against that scenario. In the event the tubing breaks, it puts nearly the same amount of gas in the air as it would have in the tank, which is not dangerous to health and safety at the 3-10psi most people keep their tanks at. The danger is if your regulator bursts and full tank PSI is released, which a solenoid can't stop.

    If your solenoid is cycling in less than 2 minutes, you need to adjust your bubble count. When I ran a calcium reactor, it took about 20 minutes to move the pH by the 0.3 pH I had the hysteresis set for (>6.8 <6.8), so I will show an example below using my set points and 20 minutes as an example

    Solenoid
    Fallback OFF
    If pH > 6.8 Then ON
    If pH < 6.8 Then OFF
    If pH > 7.5 Then OFF
    When On > 020:00 Then OFF



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  5. #5
    Frequent Visitor bigjim's Avatar
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    thanks

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    Just to add to this, make sure your friend has not confused CO with CO2.
    Carbon monoxide (CO) is the silent killer and the reason why houses (should) have carbon monoxide detectors. It replaces oxygen in your red cells and puts you to sleep. That is, if O2 and CO are present, your CO will enter your bloodstream INSTEAD of the available O2. Scary stuff usually from burning things (furnace, fireplace, garage, etc...).
    Carbon dioxide (CO2) does not get absorbed by the body; it excretes it so given CO2 and O2 availability, your body will always prefer O2. In fact, "pure air" has 400ppm of CO2. You cannot be unknowingly exposed to CO2 since it's your body's primary mechanism of detecting a lack of oxygen. When CO2 rises in your bloodstream, it will become slightly acidic and your brain will let you know you're suffocating. (Unfortunately for us, humans, we can't detect the lack of O2 so people die each year of various asphyxiation).
    So back to your original question, CO2 is the least dangerous gas since it doesn't try to enter your bloodstream and your body can detect it. It's heavier than air and a tank is probably not large enough to make a difference in your house. If you are really worried about that, there are various CO2 monitors that can send you push notifications when level rises but I'm betting that your PH will go down real quick as well so a PH alert might be all you need.

    Hope this helps

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