# Water Creep in CO2 Tube



## k-maub (Feb 10, 2007)

Hello all. I've been searching this forum all over to help me with all of my CO2 problems, and I only have a couple remaining.

I made the switch from DIY to pressurized CO2 a month or so ago, and within 2 days killed all my fish because I trusted Milwaukee and their product far too much, and I dumped 20 oz of CO2 in my tank one morning (pH < 5; Rex presumably this is a pH swing situation where fish CAN be affected?). I now realize I would have been better off with no directions misleading me to control flow with the regulator knob (if I write to them, do you think its possible to get them to modify that?).

I'd probably be better off ignoring the solenoid, but since other people have had some success, I'd like to believe I can get it to work, too. I'm more curious at this point of what physics of the problem I'm not understanding. My remaining problems are:

1) CO2 bubble rate is non-existent in the morning after the solenoid opens. To get it going, I have to open up the needle a bit, and then TURN IT CLOSED. It is the tightening of it that actually starts the bubble going. Presumably this is due to really poor craftmanship, and I need to buy a better one, but the weird thing is that if I turn the solenoid off and on within a couple of minutes (instead of 8 hours), it has no problem resuming the original bubble rate. Why would this happen? Heat from the solenoid? Backflow of water?

2) Which brings me to my second problem. Also in the morning, there is water in the tube nearly back to the bubble counter. This is despite the fact that I have a check valve (though plastic and cheap) and no water is forced back if it is not connected to anything. That is, I cannot physically suck water back through the tube when it is connected to my in-tank reactor, yet somehow, over eight hours it moves 12 inches down the tube (but doesn't start siphoning). Is this due to CO2 disolving in the water and the water displacing the absorbed CO2? At such a rate, I imagine it could make its way past the check valve. It's just bizarre to me that it's overcoming something I cannot force by sucking on it like a straw (fortunately, no one is there to take pictures of this!)

Part of getting into this hobby for me is about learning non-fish stuff, too (although I was pretty torn up about burning all my fish to death), and I'd really like to understand what's going on here and then try to fix it. Any help you can give will be much appreciated!


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## Laith (Sep 4, 2004)

Welcome to APC!  

It wasn't the pH drop that killed your fish; it was excess CO2.

As to the non-existent bubble rate, try increasing your output pressure to 1.5-2 bar (20-30PSI). That should help.

For the water in the tube, try another check valve. You're not filling your bubble counter completely with water are you?


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## Rex Grigg (Jan 22, 2004)

As Laith said it was not the pH that killed the fish but excess CO2.

It really sounds like you have a leak somewhere in the system. Either that or a totally bad regulator system. Your problem is one of the hardest to trouble shoot.

Your cheap plastic check valve is not working. You really need to get a better check valve. When the flow of CO2 is shut off the water will start absorbing the CO2 in the line and creep up the line. That's normal.

I doubt you will cause the company in question to change their directions. They make no sense at all. If you are going to control flow with the regulator knob why have a needle valve?


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## k-maub (Feb 10, 2007)

How does an excess of CO2 kill the fish, if not by changing the pH? I thought it didn't displace oxygen from the water column.

Through reading the forums, I have already learned to keep my working pressure at 30 psi. I now leave the regulator knob alone and only control the bubble rate with the needle valve. This certainly does a great deal to help the flow rate be more consistent while the solenoid is open, but it doesn't seem to help when the solenoid goes from closed to open after eight hours of inactivity.

Water absorbing CO2, it is. I have no problem getting a new check valve and needle valve (let's see, www.rexgrigg.com...), I just want to make sure I'm solving the right problem. I find it remarkable, though that the water can climb several inches up the tube by diffusing CO2. Does anyone know exactly the phsyics behind that? I doubt capillary action alone can do that.

Now Rex, how do you recommend I proceed to troubleshoot? A thorough spray-down with windex? I hear Milwaukee, though ignorant of how their regulator works, is pretty good about customer service. Is it appropriate to ask them (or who I bought it from) for a replacement yet? Or is there more I can do to make sure it is the regulator that is the problem? Presumably, you don't think this is as simple as a bad needle valve.

Thanks for the continued help, everyone!


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## Rex Grigg (Jan 22, 2004)

If you get to high of a CO2 level in the water it becomes dangerous. Just as too high of a CO2 concentration in any closed environment will become dangerous. 

Trust me. It's not the pH change that killed the fish. It was the CO2 level.

Once the water starts to absorb the CO2 you have a lower pressure in the CO2 line. So it's actually water pressure that causes and the lower pressure in the line that causes the water to creep up the line.

Windex will work to find the leaks. As will a solution of liquid soap and water. And it could well be as simple as the needle valve.


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## Laith (Sep 4, 2004)

k-maub said:


> How does an excess of CO2 kill the fish, if not by changing the pH? I thought it didn't displace oxygen from the water column.
> ...


It doesn't displace the O2. What happens is that if the CO2 concentration in the water is too high, the fish have problems expelling CO2 into the surrounding water through their gills.

CO2 normally moves from a high CO2 concentration, the blood, to lower CO2 concentration, the surrounding water, across the gill membranes. Our lungs work the same way but the medium is air instead of water.

At a certain point the fish can no longer expel CO2 from its system and dies of CO2 poisoning.


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## vic46 (Oct 20, 2006)

Just wondering but it seems to me that the behaviour of the solenoid is suspect. It sounds like it has some sort of corrosion that is inhibiting it's movement. It appears to work fine after being cycled but over time it loses it's functionality. It may be wise to give it a good cleaning.
Vic


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