Sudden co2 surge from co2 fire extinguisher cylinder

[Renzo77]

There was a sudden rush of co2 coming from a co2 fire extinguisher cylinder that has sadly killed majority of the fish in our tank, with 2 weather loaches that have been rushed to another tank with similar parameters currently recovering.

The setup consisted of the fire estinguisher with a regulator attatched that is hooked to some airline tubing and a diffuser. We set this up around 2 days ago and the psi reading that refered to the pressure in the cylinder read around 800 psi and the output being near about 0 bar yet still managed to produce some co2. We have been experiencing troubles to keep the bubbles per second a constant rate without it gradually decreasing (we tried aiming for around 1 bps). We made very small adjustments but all came out with similar outcomes and the rate gradually decreasing,

The accident happened very suddenly with everything seeming normal in the morning to suddenly all the fish floating. The regulator was covered in frost and the psi of the cylinder read around 2400 psi. I didn't manage to read how much was being released but it pretty much sounded like an airstone. The tank is around 100 litres, has a ph of 8 and a temperature of around 25-27° C.

I'd like to know from someone who has some experience with fire extinguisher co2 setups what caused this sudden increase and surge in co2 and also information on what I should do to the tank and how I should treat the current surviving fish.

 

[Colin_T]

Never used a fire extinguisher for anything except fires. Things that are used for fires should not be used for fish tanks.

I would drain and refill the main tank with dechlorinated water. Let it run for a few days and then add fish.

Don't use the fire extinguisher for the aquarium. There is plenty of CO2 in an aquarium and it comes from the air, the fish breathing, plants produce it when it's dark, and the filter bacteria and bacteria in the substrate produce heaps of it.

The remaining fish should be kept in a tank with lots of aeration/ surface turbulence and clean water. Then let them recover for a month before moving then anywhere.

 

[Salty&Onion]

Never used a fire extinguisher for anything except fires. Things that are used for fires should not be used for fish tanks.

Don't use the fire extinguisher for the aquarium. There is plenty of CO2 in an aquarium and it comes from the air, the fish breathing, plants produce it when it's dark, and the filter bacteria and bacteria in the substrate produce heaps of it.

I agree. Only things made especially for aquariums should be used in fish tanks only.

 

[StevenF]

There is no difference between a fire extiguisher CO2 tank and a CO2 tank sold by an aquarium shop. Many people have used Fire Extinguisher tanks for aquarium successfully. And one current favorite is are Paint Ball CO2 tanks.

While there is always CO2 in an aquarium it may not always be enough if there are enough plants in the tank growing well. If plants consume CO2 faster than it is getting in the water the tank PH can start to increase. Sometimes by a lot. In any case if there is always plenty of CO2 in a tank why are people using CO2 systems?

As to Renzo77's issue a little clarification is needed at one point you state the tank pressure was 800 PSI and then after the event you state the tank pressure is 2400PSI. Most full CO2 tanks will be between 2500 -3000PSI. 800PSI is a tank nearly empty of CO2. Do you have a valve between the tank and the regulator? IF so that valve should be fully open when it is running normally. Then the knob on the regulator should be adjusted to maintain the desired output pressure. Can you post a picture of yours setup?

Some possibilities is that your regulator may have failed. or your pressure readings are in error. if the tank pressure was 800 PSI that would indicate the tank was nearly empty. In a nearly empty tank the pressure will start to drop rapidly. In most regulators a drop in input pressure results in an INCREASE in output pressure. This causes a faster drop in tank pressure and a faster increase in output pressure. This is often called a sudden tank dump and it can kill fish.

At this point in time you cannot use the CO2 system on your tank until we understand what happened. Theexcess CO2 in the tank will drop as the water outgassses the excess CO2. Outgassing can be accelerated by using a air pump and stone in the tank and pumping air into the water will stabilize O2 levels in the water. A water change in the tank will also remove a lot of CO2 rapidly. Once the excess CO2 is gone the fish should start to recover unless they haver suffering brain or tissue damage.

 

[Colin_T]

While there is always CO2 in an aquarium it may not always be enough if there are enough plants in the tank growing well. If plants consume CO2 faster than it is getting in the water the tank PH can start to increase. Sometimes by a lot. In any case if there is always plenty of CO2 in a tank why are people using CO2 systems?

Partly a gimmick to sell people a CO2 system that could potentially cost a lot of money.

If you have a heavily planted tank with lots of light and fertiliser, and fast growing plants, then CO2 can help them grow even faster. But for the average aquarium, there is no benefit to adding CO2, which must be regulated and monitored closely along with the KH and pH. Otherwise you risk killing the fish.

 

[Salty&Onion]

Partly a gimmick to sell people a CO2 system that could potentially cost a lot of money.

If you have a heavily planted tank with lots of light and fertiliser, and fast growing plants, then CO2 can help them grow even faster. But for the average aquarium, there is no benefit to adding CO2, which must be regulated and monitored closely along with the KH and pH. Otherwise you risk killing the fish.

I agree. Fish breath out CO2 and ammonia anyways.

 

[Renzo77]

There is no difference between a fire extiguisher CO2 tank and a CO2 tank sold by an aquarium shop. Many people have used Fire Extinguisher tanks for aquarium successfully. And one current favorite is are Paint Ball CO2 tanks.

While there is always CO2 in an aquarium it may not always be enough if there are enough plants in the tank growing well. If plants consume CO2 faster than it is getting in the water the tank PH can start to increase. Sometimes by a lot. In any case if there is always plenty of CO2 in a tank why are people using CO2 systems?

As to Renzo77's issue a little clarification is needed at one point you state the tank pressure was 800 PSI and then after the event you state the tank pressure is 2400PSI. Most full CO2 tanks will be between 2500 -3000PSI. 800PSI is a tank nearly empty of CO2. Do you have a valve between the tank and the regulator? IF so that valve should be fully open when it is running normally. Then the knob on the regulator should be adjusted to maintain the desired output pressure. Can you post a picture of yours setup?

Some possibilities is that your regulator may have failed. or your pressure readings are in error. if the tank pressure was 800 PSI that would indicate the tank was nearly empty. In a nearly empty tank the pressure will start to drop rapidly. In most regulators a drop in input pressure results in an INCREASE in output pressure. This causes a faster drop in tank pressure and a faster increase in output pressure. This is often called a sudden tank dump and it can kill fish.

At this point in time you cannot use the CO2 system on your tank until we understand what happened. Theexcess CO2 in the tank will drop as the water outgassses the excess CO2. Outgassing can be accelerated by using a air pump and stone in the tank and pumping air into the water will stabilize O2 levels in the water. A water change in the tank will also remove a lot of CO2 rapidly. Once the excess CO2 is gone the fish should start to recover unless they haver suffering brain or tissue damage.

The regulator was attached to the output of the extinguisher and had two pressure gauges that stated the inlet pressure and the delivery pressure. We didn't realise that a more fine adjustment knob was required as the videos we've seen sometimes didn't show one. Could the lack of this second knob be the reason?

However, we do have another set-up that has a second outlet valve which helps tweak the output of co2 more accurately. The second set-up's inlet pressure gauge reads about 50 bar (which is apparently around 725psi). The delivery pressure gauge also seems to be at 0. Is the reading on the inlet pressure gauge different to the tank pressure? Just making sure if i have mistakened the two as the same thing.

Right now for the first set-up we are testing it in the same tank as we've moved all the fish to another tank and seems to be working fine as if nothing happened although we might get a needle valve for fine adjustments.

set-up 1 regulator:
https://www.amazon.co.uk/gp/product/B0711GQBJP/?tag=

set-up 2 regulator:
https://www.amazon.co.uk/gp/product/B00KPQ51IA/?tag=

 

[StevenF]

Right now for the first set-up we are testing it in the same tank as we've moved all the fish to another tank and seems to be working fine as if nothing happened although we might get a needle valve for fine adjustments.

set-up 1 regulator:
https://www.amazon.co.uk/gp/product/B0711GQBJP/?tag=

set-up 2 regulator:
https://www.amazon.co.uk/gp/product/B00KPQ51IA/?tag=

The big problem I see is that both of these regulators are designed for higher flow, and higher output pressure than an aquarium needs. They are great for delivering liters of gas per minute at pressures up to 70PSI. An aquarium only needs only a few mililiters per minute at a pressure output of only a few PSI. As a result small changes in the bottle pressure and output pressure may or may not cause the regulator to respond. Leading to flow drop and or uepected pressure surges.

People have used regulators like these successfully but fine tuning the pressure output and needle valve may take a lot of time and may not always be successful. A needle may or may not help but most find them helpful.Regulators designed for low flow and low output pressure output are available but they are harder to find and can be very expensive and still work better with a needle valve.

I think the best solution to your problem is to not use a defuser. Instead place bottle upside down in your tank with no air in it Then fill the bottle with CO2. The pressure in the bottle (probably a little less than 1 PSI pushes the CO2 out of the bottle into your tank. The bottle needs to be refilled about once a day (depends on the size of the bottle and size of the tank. The only complaint I have seen is that some people forget to refill the bottle with CO2.

In my 5 gallon I have a small bottle attached upside down to the lid of the tank and an electrical solenoid on my regulator attached to a timer periodically refills the bottle. I cannot see how you can gas your fish with this method. I am not sure how long my CO2 bottle will last with this method but I am already months past the expected refill date.

upside down bottle method.