CaRx ran out of CO2 while on vacation

[bakbay]

My CaRx ran out of CO2 around late Fri night / Sat morning, while we were out of town. I saw the drop but couldn’t do anything remotely. When I came home on Sunday afternoon, Alk got down to low 6. Everything is fine, including SPS. pH was fine the whole time but Alk dropped by 2.5 DKH. I’m slowly bringing Alk back to 8.5-9 but curious to see what you guys do? You can’t monitor the CO2 canister so set up a backup via Kalk or 2-part? Set a reminder to swap out the CO2 canister every x months?

 

[Tuan’s Reef]

Does the canister not have a meter telling you how much is left?

 

[Randy Holmes-Farley]

Does the canister not have a meter telling you how much is left?

Pressure sensing doesn't work for CO2. The video shows one weighing it to tell.

Saltcorner: Article: CO2 TANKS - PROPER CARE

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As long as a CO2 cylinder is at a reasonable, constant temperature, as gas is (slowly) used out of the cylinder liquid CO2 "boils" off as gaseous CO2, at the vapor pressure of CO2 at that temperature. This is about 860 psi at normal room temperature, or about 72 degrees Fahrenheit. This process of evaporation continues until all the liquid CO2 is gone. That is why CO2 tank pressure is constant (at a given temperature) until it's almost empty (i.e., no liquid is left), and then falls off rapidly as the remaining residual gas is quickly used up.

 

[bakbay]

Does the canister not have a meter telling you how much is left?

How many of us go look underneath the cabinet to see the analog meter? Also, my CO2 regulator doesn’t give me a “gauge” to determine how much is left. No — I can’t really do the weigh test as per the video; it’s buried underneath the tank in a corner.

 

[KStatefan]

I think I remember Richard showing a scale on his systems in one of the episodes

Put it on a PM and replace it early is how I would do it.

 

[slingfox]

You can monitor your tank's CO2 level by weighing it. All you need to know is how your tank's tare weight (ie, how much it weighs when empty) vs. how much it weighs when filled.

 

[bakbay]

So for all you CaRx users out there — that’s what you guys do? Weigh it every few months?

 

[slingfox]

How many of us go look underneath the cabinet to see the analog meter? Also, my CO2 regulator doesn’t give me a “gauge” to determine how much is left. No — I can’t really do the weigh test as per the video; it’s buried underneath the tank in a corner.

If you don't want to weigh your tank you can just keep track of how much time passes between 100% fillings and go get it filled when it has been 75% exhausted. The folks at the CO2 shop can provide you an estimate of how full the tank when you take it in for filling is but you can do the same yourself by weighing it.

 

[bakbay]

If you don't want to weigh your tank you can just keep track of how much time passes between 100% fillings and go get it filled when it has been 75% exhausted. The folks at the CO2 shop can provide you an estimate of how full the tank when you take it in for filling is but you can do the same yourself by weighing it.

It depends right? My packed SPS tank is now consuming way more Alk than a year ago. Given the current effluent rate of 55ml/min, I’ve already dissolved half of the media in 6mos. 2 years ago, not so much.

Is this what you’re doing for your CaRx?

 

[bakbay]

This is what I have: GEO 618 + customized CO2 regulator.

 

[slingfox]

It depends right? My packed SPS tank is now consuming way more Alk than a year ago. Given the current effluent rate of 55ml/min, I’ve already dissolved half of the media in 6mos. 2 years ago, not so much.

Is this what you’re doing for your CaRx?

I don't run a calcium reactor but I do have CO2 and propane tanks around the house for other hobbies/activities where I need to track tank levels. The most reliable way to get the CO2 level is weighing it. The tare weight for your gas cylinder should be stamped somewhere on the tank (usually on the dome).

See here for overview of tank markings: https://www.cryofx.com/info/co2-cylinder-markings-co2-tank-markings-cryofx/

 

[bakbay]

Alk is now at 8 and should be back to 9ish this weekend.

Well — if the only way is to accurately determine capacity is to weigh it, this can be a fun project. DIY a digital scale and send data to the Apex? Once we reach 10% remaining (mine is a 5lbs CO2 tank) — send an alert?

Or: I’m thinking of just setting up a backup 2-part and dose remotely if I’m away.

Thoughts?

 

[slingfox]

If you want to get a weight reading without pulling the tank out you could try using a hanging/spring scale.

 

[bakbay]

Basically -- something like this: https://a.co/d/hvPMBkh and somehow send the signal to the Apex.
Again, is it worth it? Maybe...but kinda fun!

 

[d2mini]

I've always used a true dual stage (not just dual gauge) regulator on mine and never had a c02 dump or got caught off-guard.
But when in doubt, always good practice to refill prior to going out of town.

 

[bakbay]

I've always used a true dual pressure (not just dual gauge) regulator on mine and never had a c02 dump or got caught off-guard.
But when in doubt, always good practice to refill prior to going out of town.

Interesting -- what do you look for? Like @Randy Holmes-Farley mentioned, you can't really determine capacity looking at the pressure regulator. It's not realistic for me to swap out/refill every single time I'll be out of town. That is, I may be out for the weekend (luckily this time) or be out for a week, sometimes two.

I'm looking for ways to build redundancy with 2 CO2 tanks in a sequence using some sorts of pressure value. Not sure if practical but will share.

 

[o2manyfish]

There are 2 methods for keeping track of the C02. However, given your situation of having been out of town, neither would have made any difference.

Easy Version: Add a pH probe to your Calc RX Canister. Depending on your Reactor and Media there will be an ideal pH that the reactor is always at. For example in my Dastaco using Dastacto/Triton Media the Calc Rx runs at a pH of about 5.4. As soon as the pH gets to 6 I get an alert letting me know it's time to change the CO2 tank.

Now this only works once the tank runs out and you have to be home to resolve the issue.

Complicated Version: Add a Digital Pressure Gauge. There are a diverse variety of highly sensitive digital pressure gauges that accurately measure pressures in the range we need for our CO2 systems down to .02 psi. Without spending a fortune (Sub $100) you can find Chinese units that run on 12v and have a 0-10v output. These gauges are usally on a 1/2" MPT Connector. So you have to add a 'port' on the tank side of your regulator.

Once installed you have a very accurate tank gauge. But with the 0-10v output you can connect the output to any controller to monitor the pressure level in the tank. For the couple of Aquarium Monitors on the market, these are not delicate (or accurate) pieces of equipment - you will get very general readings from the 0-10v output - enough to set a full value and one when the tank pressure has dropped to a set level.

Or you can very easily build your own mini PLC controller that has a 0-10v sense input - much more sensitive than any aquarium controller on the market, and connect the PLC output to something as simple as a light or a buzzer to let you know when the value has dropped below a set value.

I have a few versions of the PLC version and they work really well. But in my particular application my CO2 tanks (2 50lb tanks) are outside and the Digital Pressure Gauges I have played with have a very short term life being exposed to any environmental changes or drastic changes in humidity (rain to summer - even if it doesn't get wet).

The pressure in the C02 tank stays stabile until it starts to run out. On my high C02 consumption system I get about 2.5 to 3 days before the tank is totally dry - to the point the pH probe in the Calc Rx Chamber kicks in. Double Safety.


Dave B

 

[d2mini]

Interesting -- what do you look for? Like @Randy Holmes-Farley mentioned, you can't really determine capacity looking at the pressure regulator. It's not realistic for me to swap out/refill every single time I'll be out of town. That is, I may be out for the weekend (luckily this time) or be out for a week, sometimes two.

I'm looking for ways to build redundancy with 2 CO2 tanks in a sequence using some sorts of pressure value. Not sure if practical but will share.

Not sure what you mean. That's the whole point of the one gauge on the regulator. One shows your output pressure and the other shows the pressure in the tank. As it starts getting low the needle starts to drop. The cheap single stage regs will not show this and "dumps" at the end.

20150806_DSC9369_200gReef by Dennis, on Flickr

 

[bakbay]

There are 2 methods for keeping track of the C02. However, given your situation of having been out of town, neither would have made any difference.

Easy Version: Add a pH probe to your Calc RX Canister. Depending on your Reactor and Media there will be an ideal pH that the reactor is always at. For example in my Dastaco using Dastacto/Triton Media the Calc Rx runs at a pH of about 5.4. As soon as the pH gets to 6 I get an alert letting me know it's time to change the CO2 tank.

Now this only works once the tank runs out and you have to be home to resolve the issue.

Complicated Version: Add a Digital Pressure Gauge. There are a diverse variety of highly sensitive digital pressure gauges that accurately measure pressures in the range we need for our CO2 systems down to .02 psi. Without spending a fortune (Sub $100) you can find Chinese units that run on 12v and have a 0-10v output. These gauges are usally on a 1/2" MPT Connector. So you have to add a 'port' on the tank side of your regulator.

Once installed you have a very accurate tank gauge. But with the 0-10v output you can connect the output to any controller to monitor the pressure level in the tank. For the couple of Aquarium Monitors on the market, these are not delicate (or accurate) pieces of equipment - you will get very general readings from the 0-10v output - enough to set a full value and one when the tank pressure has dropped to a set level.

Or you can very easily build your own mini PLC controller that has a 0-10v sense input - much more sensitive than any aquarium controller on the market, and connect the PLC output to something as simple as a light or a buzzer to let you know when the value has dropped below a set value.

I have a few versions of the PLC version and they work really well. But in my particular application my CO2 tanks (2 50lb tanks) are outside and the Digital Pressure Gauges I have played with have a very short term life being exposed to any environmental changes or drastic changes in humidity (rain to summer - even if it doesn't get wet).

The pressure in the C02 tank stays stabile until it starts to run out. On my high C02 consumption system I get about 2.5 to 3 days before the tank is totally dry - to the point the pH probe in the Calc Rx Chamber kicks in. Double Safety.


Dave B

Thanks Dave - very insightful. I can detect if I run out of CO2 (regulatory is on but pH inside the CaRx spiked) so that's not a problem.

Will this ultra low-tech way work? I'm thinking of daisy chaining two CO2 tanks with two "T-connectors", one closer to the CaRx and another one at the opposite end. When the pressure closer to the CaRx runs out (no more CO2), the second tank takes over. I have zero experience with this -- just thinking out loud! lol

 

[bakbay]

Not sure what you mean. That's the whole point of the one gauge on the regulator. One shows your output pressure and the other shows the pressure in the tank. As it starts getting low the needle starts to drop. The cheap single stage regs will not show this and "dumps" at the end.

20150806_DSC9369_200gReef by Dennis, on Flickr

I have something similar -- believe it to be custom-built by "Alan Le"? However, unless it's broken but I don't recall observing the right gauge going from ~1000 psi to zero.