Should I top up my CO2 tank?

[Heuer]

Hi folks,

I realise my 5L CO2 tank's left side gauge is starting to drop from about 1000 when i first bought to about 800 after 8 mths. Is this time for me to top up. How long will it last as currently i am setting it at about 3 bps.

Thanks

[tawauboy]

you can top up now.
don't wait until the pressure drops to zero.
with co2 still in the tank, the refiller can release some of the remaining co2 to cool the tank. this will help in the refilling process.

[Heuer]

thanks for your advice. Hope the remaining CO2 can last me till this weekend. do you think so?

Cheers!!

[tawauboy]

should not be a problem.
else rig up a diy co2.

[elmike]

Question for tawauboy...

I have seen CO2 tanks in a lfs running good at 600psi. Wouldn’t it be a bit premature to send for refill at 800 psi?? Given different models of gauges/ regulators, wouldn’t it be better, at least the 1st time, to wait and see how the rate of bps tails down?

This is one way of identifying the threshold “to-be-top-up’ psi for each individual set. What do you think?

[vinz]

I haven't been tracking mine consistently, but my 5 litre cylinder supplying to a 6 foot aquarium can last a few weeks from the time the pressure starts to drop. I usually get mine topped up the weekend after it goes below 200psi.

[bclee]

Let me try to help to give you an idea how much gas is 800psi.

Conditions/Assumptions:
Pressure guage is accurate
Isothermal condition (25°C)
Gas cylinder volume: 5L
Bubble rate: 1bps
Bubble size: 0.07cm³ (bubble diameter = 0.5cm)
CO2 duration per day = 12h

5L of CO2 at 800psi is equivalent to about 440L at atmospheric pressure.
Therefore, at the assumed bubbling rate and duration, it should last 145.5 days.

5L of CO2 at 200psi is equivalent to about 77L at atmospheric pressure.
Therefore, at the assumed bubbling rate and duration, it should last 25 days.

This is just to give you a rough idea...

BC

[tawauboy]

[quote:96d87e8e83="elmike"].............

I have seen CO2 tanks in a lfs running good at 600psi. Wouldn’t it be a bit premature to send for refill at 800 psi?? [/quote:96d87e8e83]

when you send your tank for refill is subjective. for lfs, i think they may be using those huge cylinders, so even at 600psi, they will have plenty of gas left.

knowing the threshold for when to refill is good. just note that there are aquarist that experienced 'end of tank dump' when pressure dropped below the regulator's regulation pressure. however, if you are using a needle valve, this is not an issue.

[taysh75]

Let me try to help to give you an idea how much gas is 800psi.

Conditions/Assumptions:
Pressure guage is accurate
Isothermal condition (25°C)
Gas cylinder volume: 5L
Bubble rate: 1bps
Bubble size: 0.07cm³ (bubble diameter = 0.5cm)
CO2 duration per day = 12h

5L of CO2 at 800psi is equivalent to about 440L at atmospheric pressure.
Therefore, at the assumed bubbling rate and duration, it should last 145.5 days.

5L of CO2 at 200psi is equivalent to about 77L at atmospheric pressure.
Therefore, at the assumed bubbling rate and duration, it should last 25 days.

This is just to give you a rough idea...

BC

My co2 tank is 3.5L which dual gauge regulator. Recently for about a week +, the pressure start to drop to "800kg/in2" and" 30kg/in2".
It is time to refill? Or when is a good time to refill. Any advice pls. Thanks!

[tawauboy]

there is no hard and fast rule of when you should refill. if you are usually busy or cannot afford to run out of co2 for a few days, refill when the pressure starts to drop.

if you can "afford" to run out of co2, let it empty. take note of the number of days taken for co2 to empty. this gives you a good gauge of long your co2 can last.

some places allow immediate co2 top up so you can refill when your co2 runs out.