CO2 schedule ?

[Totenkampf]

SOVs that are used in our systems need to be fail-closed. That way you can use them to kill CO2 on a timer at night, with a power outtage, or with a pH controller. The system you describe sounds nice for sure. You can even manifold the two cylinders together with two regulators, just set one 5 PSI higher than the other and one will be exhausted first (the other will only act to compensate for a pressure 'boost' when the primary starts to tail off.) this will allow you to have plenty of time to get a fill on one while no interruption of service. we use this trick on analytical equipment. Set it up as:

cylinder(s) -> DSPR(s) -> quad manifold -> SOV on each leg (if using four pH controllers) -> metering valve (better than needle valve)

note: pressure regulators control pressure, meedle valves control flow. set your PRs and THEN tune each NV for the BPS you want although this wont matter as much if you are using a pH controller. In this case the NV is a second line of defence from dumps (the dual stage regs and dual cylinder manifold will prevent this 99% of the time so a normal NV would be okay and half the cost of a metering valve) and will only control how quickly the pH will shift when the valve is opened. I still think slower is better and would set it up like you normally would without a pH controller. I have some high end DSPR made by the company GO and a couple ASCO continuous duty SOVs and 1/8" tube swagelok SS-SS2 metering valves that i was going to build up and sell. I may cut a deal for just the loose parts if you are interested.

[Complexity]

I've never tried to run more than one tank from a single CO2 system, but there are a couple of things I might can help with.

Each pH controller would need to have its own solenoid plugged into it so four pH controllers would require four solenoids. The pH controller is plugged into the electricity and the solenoid is plugged into the pH controller. When the pH controller measures the pH to be equal or lower than what you've set, it stops dosing the CO2 by shutting off the electricity to the solenoid. So in a way, the pH controller is basically an on/off switch for the solenoid based on the pH reading in the tank. Therefore, you cannot have four pH controllers, each reading the pH in four different tanks, without having four solenoids, as well.

How you can connect four solenoids to one regulator is something I don't know. Basically, the regulator controls the pressure that's coming from the cylinder so the CO2 doesn't come out all at once. Then the needle valve fine tune's the pressure from there. I don't know exactly how the solenoid works, but it's what connects the electricity to the regulator so it can do its job.

If you need four solenoids to run four pH controllers, and a solenoid connects the electricity to the regulator, it would seem you would need a separate regulator for each solenoid. The conclusion then is that you're not really saving much by running four regulators from one CO2 cylinder, so you might as well get four cylinders and run each system independently.

All that brings me to the conclusion that the there are only two reasonable ways to run four tanks with one CO2 cylinder. The first is to simply give up the idea of using a pH controller (and all that entails). The second would be to combine the water of the four tanks so that they're all running the same water supply. This could be done through combined filtration. Then the CO2 would be the same in all the tanks from the single CO2 system. The main concern there would be in ensuring that the CO2 embedded water (coming from the reactor) got distributed evenly in all four tanks. There are pros and cons to either method.

There may be other ways to do this that I'm not familiar with. It would be best if you could get in touch with people who have actually rigged up a system like you're wanting to give you some ideas of how they did it and what pros/cons they experienced with their setup. If you don't find anyone who can help, send me a PM, and I can point you to a couple of resources that might have more experience with this kind of thing.

[Bedlamer]

I’m just starting to research CO2 systems for use with planted tanks. I’ve never used the yeast or bottled method before. I am familiar with gas systems used in SCUBA, paintball and medical O2. I’ve had a chance to briefly examine CO2 systems in some folks homes and in LFHs. Thank you to those who have contributed to this thread—it’s been a good starting point. I’m really not familiar with solenoids. I understand that SOVs are electro-mechanical valves that can be controlled by such things as pH controllers and timers. Does the signal from the timer or controller usually cause the valve to open or close—i.e. do they fail open or closed--or does it depend on the application?

If you were doing a money is no object bottled CO2 setup for multiple planted tanks—let’s say four of various sizes—do I have the following design correct—or is there something I’ve messed up?

Two bottles, one in use, one for a spare refill to have on hand. Master on/off valve as part of each bottle. Dual stage regulator i.e. one of these linked earlier http://greenleafaquariums.com/co2-re...regulator.html with quadruple needle valves and bubble counters option. Then four separate solenoids controlled by four separate pH controllers (one for each tank) to CO2 specific tubing to a one way check valve to more tubing then to either a diffuser or a reactor?

One thing I’m not clear on is the placement of the SOVs in the system—could they be as I described with the dual reg above or would it just be one SOV for the whole system and the quadruple outputs would just be for multiple diffusers on one huge tank if you wanted it run by a pH controller—and you would need four totally separate systems to run four tanks? Or the dual stage reg linked above would come with one SOV and you could easily add four more SOVs to provide for a four separate tank setup?

Thanks in advance for any input to help me get a handle on this.

[gardentank]

Oh yeah and avoid end of tank dumps at all costs! I'm looking for a 25 pound bottle to buy so I can swap my tank the second my main pressure begins to drop. I learned the hard way (killing the entire tank, including a group of 2 year old roseline sharks... Never again!!!) to refill the same or at least the next day as soon as I see a pressure drop. I look at the main pressure everyday and the second I see it move I shut it off. If you have a 55gallon or bigger or if you think you will want to run co2 to multiple tanks from one bottle in the future then get the biggest tank you can afford / find room for. Refilling a 5lb costs me 8 bucks and 25lb refill cost like 17 bucks. The price difference on the bottles themselves is like 80 or 100 bucks up front but worth it in the long run.

[gardentank]

I removed my solenoid and run it 24/7 without having to plug it in anywhere. My emperor and diamond tetras have been breeding nonstop since I started running it all the time. I'm assuming that is because the ph stays stable and low around 5.8 to 6.0. Check out my pics they speak for themselves as far as the plants are doing!

[Raul]

yep going to get me a spare paintball tank trying to find a 36oz one and have it ready, then when it drops I just replace and go and refill

[Complexity]

And to continue with what totemkampf just said, when you see the main pressure begin to drop, not only should you start planning to get a refill, but you should actually get the refill. Don't wait for the the pressure to drop all the way. It is the loss of pressure that causes end of tank dumps. So when the pressure begins to drop, the end of tank dump is approaching. CO2 is cheap. So go ahead and get the refill right then to avoid the whole end of tank dump issue altogether.

Personally, because of my schedule, I now have a spare 10lbs cylinder on hand for this reason. That way, when the cylinder I'm using begins to lose pressure, I can just swap out cylinders immediately, and then I have plenty of time to get the empty one refilled.

[Totenkampf]

i didnt know SA would do paintball fills, good to know. they fill the tanks with liquid CO2, thats why they weigh the tank to fill it. as the vapor co2 is used, more liquid offgases (decompresses) to fill the void left by the vapor that you are using. when a liquid decompresses, the vapor will often expand to take up 50x or more volumeof the original liquid and so this causes the pressure in the tank to stay level unitl the liquid is exhausted. when u see the pressure start to drop, you need to plan on a fill soon. the liquid issue is also why the cylinder should be upright so that you dont get this liquid into the valve where it can rapidly expand and/or freeze up the regulator.

[Raul]

for now everything seems leak free, no dumps in the morning and looks all stable, so I am happy now, tank is doing so well and still as a refugium and decided to run the CO2 24/7 untill i can get the controller.

but one thing I notice I had the CO2 paintball tank it is a 24 oz, and prior to my leak, it had already 2.5 weeks runnning and didn't had a drop on the highpressure and I am running like 3 ~4 bps, I am glad it lasts just because it is easier to go and fill it up at sports authority than go to a welding or beverage supply store since there are none close enough.

[Totenkampf]

you can add the SOV inline anywhere after the regulator and it should work the same. i usually only use teflon tape and it works the best if installed correctly. by correctly i mean dont put any on the first thread of the fitting (it can shred off and clog the small orifice in the SOV or NV) and only use 2.5-3 wraps. pipe dope is good if you dont glob it on and do spread it around evenlyall the way around before you install but its more prone to leak.

[Complexity]

I'm glad to hear you didn't suffer any losses! It can take some time to get it all adjusted, but you'll eventually work the kinks out.

[Raul]

i used great white pipe joint compound for the new fabco.

[myjohnson]

Did you use teflon tape?

[Raul]

Yes I had both needle valves the one from the MA957 was wide open so the pressure was on the hose since I was restricting the flow with the nv-55, but well now no more MA957 needle valve, been monitoring the whole day and it is more stable now been checking with soap and water mix on the all the connections to see if there is any leak since I had to remove the solenoid and the original NV to set the new one.

[Totenkampf]

@vicki - WOW you have been busy! good stuff. i may have to see if i can source a low cost but high quality DS reg setup which would include a continuous duty SOV and a high grade metering valve. i know i can but a concoa brass dual stage, asco 120VAC SOV, and a swagelok SS-SS2 together for about 4 bills but thats not beating people up on pricing.

@raul - you're going baller on us son! high tech here you come! so did you have BOTH needle valves installed when you hade the leak? the downstream side of the pressure regulator should never build to full set point pressure unless the outlet is blocked. if you had both NV installed and the plastic tubing in between then yes that could have been dangerous. on a side note, the milwaukees regs seem to run better at 25-30 PSIG, lower then that and they falter (as told to me by a long time user)