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To the Experts on Planted Tank

I recently received a pre-owned regulator from a fellow member of my local aquarist club – a Red Sea Paintball pro package. The member even threw in a still filled CO2 cylinder. Great!

I want to use this system as part of an aquascape overhaul for an existing tank that is now running for just of three years. Upon initial set-up I was still very green but this tank became a great learning tool for a fascinating hobby. In the past two years I actually set up three quite attractive nano-scapes using defunct lab glassware. For the starter tank though, at present, I would be extremely generous to call it a ‘jungle scape’. Despite the total absence of scaping and general chaos in plant arrangement the tank is very stable, obviously well matured. Fish and plants are very healthy and water quality – chemistry and clarity – is superb.

So I decided to give the Red Sea regulator a test run on a stable and very reliable planted system before the big overhaul.

I have now been running the paintball set up for about a week.

Here’s what I did and how the regulator behaved:
Although the set came with a CO2 reactor, bubble counter and needle valve I did not use those since I already have equivalents already integrated into the tank. With the prior DIY CO2 set up I used a glass spiral diffuser, situated under the filter outlet, which doubles as a bubble counter. The fine ‘spray’ of bubbles gets whisked by the filter outlet stream and many of the tiny bubbles dissolve into the water before they reach the surface. And I did not like the Red Sea needle valve, the inline rotating halves made adjustments very cumbersome when it twisted the CO2 tubing. Its gradations were also not fine enough to set a consistent flow. This I replaced with a Swagelok needle valve using lab grade Nalgene tubing – sturdy, taking high pressures and attaché securely to regulator and needle valve fittings with no leaks, nor pop offs.
I also added a low voltage (12 V) solenoid valve to cut CO2 during lights off. And here is where the regulator started to behave strangely. Hopefully your experience with similar systems may help me clear some things up.

Let’s start at the beginning:
Connecting the regulator to the full cylinder immediately snapped the needle of the Cylinder Pressure gauge to about 70 bar (the sweet spot for the full cylinder). Then turning the top knob allowed audible CO2 flow from the outlet. Blocking this flow then with my thumb showed a response in the Working Pressure gauge. The Red Sea instruction manual states that the regulator should be set at about 1 bar working pressure for standard use. Holding my thumb in place I set it at 1 bar and tested the consistency by blocking and releasing flow with my thumb a few times. This seemed OK. So then I decided to connect the solenoid valve, leave it in the off/closed position and check whether, at 1 bar, the valve is leaky (the particular brand can take a lot more pressure than 1 bar but I had to check).
However, now the regulator started to misbehave. The Working Pressure gauge needle, after being set at 1 bar, slowly started to creep up the pressure - as if there was a slow leak between the two stages in the regulator - and continued until the needle twisted all the way around against the stopping pin at zero. And then it remained stuck there. Thus, no more functional Working Pressure gauge.

But at least the solenoid did not leak.

From almost two decades’ experience with lab and industrial regulators I knew I could work around this so I forged ahead.
Switching the solenoid open released the pressure in a swift burst – but then the regulator remained closed. No CO2 outflow. On larger lab and/or industrial regulators this usually means working pressure was set too low and creeped shut by itself (in my younger days I lost quite a few data collection runs due to this common error of over cautiousness). So I slowly increased the working pressure (ostensibly well above the instruction manual’s recommended 1 bar, having to work blind on the stuck working pressure gauge).
After a few trials I found a working pressure that would restore flow once the solenoid was switched open after being closed for 20 minutes.
So I set it up in the tank, adjusted the needle valve to 2 bubbles per second, and set up a twin drop checkers to indicate about 30 ppm CO2 for the tank.

Check this site -- -- for an online calculator and methods how to set up a twin drop checker system to get a targeted CO2 concentration. Basically you make up two solutions, one at 2.93 dKH and one 5.26 dKH. If both turn green you know you’re maintaining a dissolved CO2 concentration between 22 and 39 ppm – most likely 30 ppm. Fish are comfortable and plants are very happy.

So I got the CO2 system running, early evening, and the drop checker solutions just started to shift from blue to greenish blue when the timer switched lights of. Now the test was for lights on next morning.
Next day the lights went on and no CO2 flow. Cylinder Pressure was still at 70 bar. Thus no overnight total CO2 loss. So the deduction was that working pressure was still too low. This required about two more days of upward adjustments of working pressure.

Now I have the system set that, with lights on, it takes about 30 minutes, after the solenoid opened, for the set flow to stabilize.
Upon the solenoid opening I get a burst of released pressure, and then no, or very low, initial CO2 flow. Then slowly flow establishes until about 1.5 to 1.75 bubbles per second. After one day of this ‘stabilized’ flow the drop checkers read light lime green on 2.93 dKH and bright green on 5.26 dKH – meaning that CO2 is slightly above the targeted 30 ppm. Slow adjsutments on the needle valve will correct this.
For all the hassles I actually have a working automated system. And after a week the needle has barely shifted from 70 bar. So there is very economical CO2 use.

Now, a few quick questions:
Are hassles running a Red Sea Paintball system where the working pressure behaved inconsistently a common occurrence?

What really bothers me is the apparent ‘leak’ from cylinder stage to working stage, in the regulator, pressurizing the system up to the solenoid. Have anyone noticed a problem like that before?
I think this means I may now have, functionally, a single stage regulator.
Do I risk end of tank dump?

If this is a known problem, can I fix it myself by opening the inner workings and cleaning, reseating, adjusting the inner bits (diaphragms etc.)?

Or would it be fine (low risk) to just keep the system as is?


CJ Klok
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