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Reactor and working pressure PSI

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I have a question regarding CO2 reactors and working pressures. So I have read in some other posts here on the forum that for reactors, you generally need less pressure to operate as the only pressure you need to overcome is the water pressure.

How does one know if one has enough working pressure? My intuition tells me that so long as stuff is going into the regulator, congratulations you have enough to operate. And a follow up question is, does this mean that increasing the working pressure doesn't really change how much CO2 is being injected so long as a threshold is being met?
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Discussion Starter · #3 ·
Are you talking about a CO2 generator? As in baking soda and citric acid? Or are you talking about CO2 over calcium carbonate?
Im talking about standard CO2 regulator setups with pressurized tanks. Since your regulator has a "working pressure" that it is down stepping the CO2 tank pressure to. Obviously if that is set to like 1 PSI, you probably won't have enough to run anything. Im just curious as to how you can tell if you have set an adequate "working pressure".

So for example, diffusers require a lot more working pressure to operate, as theres more resistance against the gas. So there must be some threshold where there is enough PSI to push through the resistance. However, my question is, once you have reached that threshold, does increasing it further do anything as we typically have needle/metering valves to fine tune the output. I hope that sorta makes sense what im getting after? Perhaps there is a better way to phrase what I'm trying to get some insight into.
 

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You typically set a regulator to ~20-30psi. This is your working pressure, after it has been stepped down from the high pressure. From this point, you introduce a metering valve into the equation, and you don't really think about the pressure on that side of the business.

The truth is, the "working pressure" isn't all that important, to a large degree. You wouldn't set it to 1 psi, because changes in ambient temperature could negate your pressure, to the point that nothing flows - or the flow would be unstable, and the output inconsistent. I also want to say (if memory serves) that a typical one way (check) valve needs about 2-3 psi to open. On the other hand, if you have more than 30 psi, you may find that a solenoid (of the category that we'd normally use) could have trouble operating against the pressure. So, this is the working pressure range that has been found to be stable in most climates, assuming household climate controls.
 

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Discussion Starter · #5 ·
You typically set a regulator to ~20-30psi. This is your working pressure, after it has been stepped down from the high pressure. From this point, you introduce a metering valve into the equation, and you don't really think about the pressure on that side of the business.

The truth is, the "working pressure" isn't all that important, to a large degree. You wouldn't set it to 1 psi, because changes in ambient temperature could negate your pressure, to the point that nothing flows - or the flow would be unstable, and the output inconsistent. I also want to say (if memory serves) that a typical one way (check) valve needs about 2-3 psi to open. On the other hand, if you have more than 30 psi, you may find that a solenoid (of the category that we'd normally use) could have trouble operating against the pressure. So, this is the working pressure range that has been found to be stable in most climates, assuming household climate controls.
Yea I mean that's generally what I have been doing, I was curious more to an explanation behind the mechanics of this hehe.
 

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When I switched from a diffuser to a reactor, I turned the pressure down on my Milwaukee regulator basically as low as it would go to give me the bubble count I wanted with the needle valve open. This was based on the (wrong) instructions* that I got with the regulator. When the solenoid would open in the morning, CO2 would rush out, and probably if I hadn't caught it, I'd have gassed my fish.

I run it at about 25-30 psi now and use the needle valve to control the rate, and it is much more stable.

I'm also in the process of building a new, higher quality 2 stage regulator so I can retire the Milwaukee.

Moral of the story is, in my experience, stay away from really low pressures, at least in the Milwaukee regulator, because it's unreliable - even though a reactor could theoretically work with relatively low pressure. Bump up the pressure and control with the (not very good) needle valve.

*Interestingly, the Milwaukee regulator I got came with instructions suggesting that bubble count be achieved by turning the pressure regulation knob with the needle valve almost fully open, and just "fine tuning" with the needle valve. This worked somewhat OK with a diffuser which ended up needing a decent amount of pressure to work, but not at all with a reactor.
 

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Fwiw, I run all of my regulators at 15psi in combination with reactors. The motivation was having published flow rates at 15psi for my flow meters. I don't think there's any reason to go higher in my case. Just providing another data point.
 

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You're going to negate that pressure if you have a metering valve, anyway. As I mentioned before, it's more or less just a means of setting a pressure that works with both ambient room temperature fluctuations, and the mechanical limits of a solenoid. (if you have one) So if a lower pressure works in your case, there's no reason not to do so. More refined solutions for more educated users, is always the rule.
 
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