Dennerle Check Valve, bad? - The Planted Tank Forum
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post #1 of 6 (permalink) Old 03-26-2013, 01:48 AM Thread Starter
Algae Grower
Join Date: Oct 2009
Location: Phila Suburbs
Posts: 132
Dennerle Check Valve, bad?

Ive had this valve in service since December 2012 and havent really thought about it since I installed it.

Today I noticed after a few hours of co2 that the PH was pretty high and my drop checker was blue.

After diagnosing various things with the regulator itself, I realized that the co2 wasnt getting past the Dennerle valve.

The valve itself is actually leaking. If I stick it in a cup of water, bubbles are coming out of the nuts that lock the tubing on.

Ive removed the valve and am trusting my Swagelock check valve that sits under the JBJ bubble counter to protect my co2 system. However, if the airline decides to pop off the bubble counter, I'm in big trouble as the tank will drain!

So, is this fixable or just needs to be replaced? Anybody dealt with warranty replacements with Dennerle? I purchased the valve from ebay from 'petstore-web' I'll contact them tomorrow.
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post #2 of 6 (permalink) Old 03-26-2013, 02:20 AM
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Location: Canada
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Am I the only one having no problems with the cheap-o 2 dollar check valves? Do you have oil in your JBJ Bubble counter? I'm not sure how one could get water past a check valve, oil and then the built in check valve of the counter (I wouldn't trust that check valve alone) but you have to agree that a hard feat to do.

Water -> Check valve -> Oil -> Build in check valve.

Then again, I don't have the JBJ Bubble counter, I have the knock offs. I even ran water straight from the sink, it didn't past. You can try those DICI Bubble Counters, maybe the knock offs are, dare I say, better?

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post #3 of 6 (permalink) Old 03-26-2013, 02:28 AM Thread Starter
Algae Grower
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Location: Phila Suburbs
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My "JBJ" check valve is a JBJ knock off from e bay. Its filled with water.

Let me clarify my setup.

I have it like this:

CO2 tank -> Solenoid -> Metering Valve --> Swagelok Check Valve --> Bubble Counter (with check valve built in that I dont trust) --> Silicon Hose --> Dennerle Valve - > Silicon Hose -> Cerges Reactor --> Return to tank

So you're correct, it would be hard to get the water into the co2 equipment.

However, my concern is if the tubing popped off the bubble counter, the water would immediately backflow and it would be disasterous. The chances of this are unlikely, but even without that Dennerle valve there I couldnt even disconnect the tank from the system, say for a refill, without having to deal with the water siphoning back.
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post #4 of 6 (permalink) Old 03-26-2013, 02:56 AM
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Location: Greensboro, NC
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A quick, temporary fix would be a couple cheap plastic cv's from your LFS. And if the top of your JBJ-style cv has a little nut on it, it's a compression fitting, so the tubing popping off of that is highly unlikely unless the tube wasn't on the barb all the way.

I've heard of a Swagelok cv failing maybe once, so you're probably okay there.

And I believe there are some inline 1 psi Swagelok cv's on Evilbay for under $20 shipped, if you're interested. Though you'd need a couple tube inserts.
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post #5 of 6 (permalink) Old 03-26-2013, 03:23 AM Thread Starter
Algae Grower
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Location: Phila Suburbs
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Yea, it is a compression style nut. Came with a little o-ring as well so I put the o-ring on the tubing, slide it onto the barb, push the oring down, then tighten the nut.

Sometimes the tubing starts to twist with the nut, and it can back off the barb a bit. So you just gotta make sure you're secure, because I had it pop off when I was working on it.
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post #6 of 6 (permalink) Old 03-26-2013, 09:54 PM Thread Starter
Algae Grower
Join Date: Oct 2009
Location: Phila Suburbs
Posts: 132
Without the Dennerle valve today, my co2 system is acting completely different!

Im definitely getting more co2 into the tank, but at the same bubble rate.

I know this because:

My PH is much lower at lights-on time than it usually was
Drop checker is yellow at lights-on time, previously it was a greenish

Im wondering if I should even put it back on. Will I have the same problem?

When my co2 is off, there's water pushing at the outlet side of the valve. Im assuming the valve was designed just for this purpose, right? Could that water back pressure be making the valve fail?
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