# How Long Does Your 10lb CO2 Tank Last?



## Sunny

I'm running a 10lb CO2 cylinder on my 90 gallon tank that is fed into a Rex
Grigg type reactor. I have a greenleef drop checker at 30ppm, and tank and plants are thriving well ( Amazon Sword Flowering ) My 10lb cylinder is lasting approx 2 months . How about you?


----------



## Mr Fishies

That sounds like a pretty quick empty to me too. If so, what bubble count is it running at, my 10lb tank at 3 bubbles/sec sets me up in a 75 pretty well for something like 4-5 months. My CO2 hits ~30ppm 2-3 hours after everything turns on - lights & CO2 on for 10 hours.

Do you have a bubble counter?

Have you tried painting your CO2 connections with a 50/50 solution of dish soap and water to check for leaks?


----------



## Sunny

Mine has a bubble counter but I have it controlled by a ph probe and solonoid that turns it on and off when needed. This time I'm going to set the bubble counter at 5 bubbles/sec and see what happens.


----------



## Darkblade48

I would say that you have a leak somewhere as well...a 10 lb tank should last more than 2 months.


----------



## Mr Fishies

So, if you're setting it to 5bps...is that turning it down or up?

If you're running more than 5bps, were you seeing bubbles being ejected from the output of your filter/pump that drives the reactor? Not tiny little ones caught in the flow, but ones big enough to rise to the surface. If so, there's possibly some of your lost CO2. Under idea/perfect world type conditions a reactor will only eject water with CO2 dissolved in it and no bubbles.


----------



## Sunny

5 bubbles/sec would be turning it down....I have no bubbles after the reactor leading me to think that I'm getting 100% saturation of the Co2. I have had it set at 5 bubbles/sec all day and replaced the drop checker fluid with fresh and it's still in the green so I will see how long this cylinder lasts.


----------



## Chris S

Mr Fishies said:


> So, if you're setting it to 5bps...is that turning it down or up?
> 
> If you're running more than 5bps, were you seeing bubbles being ejected from the output of your filter/pump that drives the reactor? Not tiny little ones caught in the flow, but ones big enough to rise to the surface. If so, there's possibly some of your lost CO2. Under idea/perfect world type conditions a reactor will only eject water with CO2 dissolved in it and no bubbles.


If he is using one of Rex's reactors, then he should be getting %100 of the co2 dissolving if the filter/pump that is pushing water through is strong enough.


----------



## Mr Fishies

Chris S said:


> If he is using one of Rex's reactors, then he should be getting %100 of the co2 dissolving if the filter/pump that is pushing water through is strong enough.


What I was trying to determine is if perhaps his reactor was filling with a cavity of CO2 far enough down the reactor that the stream of water was pushing gaseous CO2 out as bubbles rather than dissolving it. In terms of strong enough - there is such a thing as too strong a pump for a given (length of) reactor and too strong a flow will blow bubbles right out the bottom of the reactor.



Sunny said:


> 5 bubbles/sec would be turning it down....I have no bubbles after the reactor leading me to think that I'm getting 100% saturation of the Co2. I have had it set at 5 bubbles/sec all day and replaced the drop checker fluid with fresh and it's still in the green so I will see how long this cylinder lasts.


If there are no leaks, it sounds like you are/were pushing a lot of CO2 into that reactor - do you know how long the system runs (roughly) when it injects CO2? I've never really played around with PH controller type set-ups - does it do frequent bursts of CO2 or big dumps once in a while?

Like an overpowered furnace (too many bps) making your house too hot when it runs then a long wait for temp to drop several degrees then overheating again. Maybe tuning the bps can help.

Would be it a problem/worth considering a timer so it only injects CO2 during lights-on/daytime?

I'd still check for leaks. Is there anything other than a single length of airline between your bubble counter and reactor that could be a weak/leaky connection?

The only other thing that comes to mind is that your 90 has a sump does it not? Maybe the overflows/downpipes and splashing of water is making your CO2 off gas really quickly - like stirring a glass of pop with fork - requiring more CO2 to be injected.


----------



## Chris S

A wet/dry sump would do exactly that, gas off a lot of co2.


----------



## wtac

Sound to me that there is a leak somehwre in the system. There are some clients that I have the Ca Rx @5bps and last at least 12months.

What CO2 regulator are you using? I've had the worst experiences w/AquaMedic, ie 10lbs @3bps lasting 2 weeks.


----------



## Sunny

I am no longer using a wet/dry system, now it is a complete closed loop. Everything is controlled by a Milwaukee ph meter through a Milwaukee regulator. The Greenleaf drop checker turns green at a ph of approx 7.0 at 5 bubbles/sec. I was using more Co2 to fight algea and turn the drop checker to light green, I moved the tank to a darker area of the house and cut my lights back to 5 hours total.The algea appears to be non existant now so that is why I have cut the Co2 back to 5 bubbles/sec. Theoretically this should make my Co2 cylinder last longer.


----------



## wtac

What type of tubing are you using? If you are using silicone airline tubing, the CO2 seepage is 72x greater than if used the polyethylene (PE) tubing used for RO/DI units. Factor in the length of tubing used, that might be the issue.

You can use the 1/4" WATTS tubing (pink stripe on tag) found @Home Depot.

Ideally, flouroethylenepropylene (FEP)/FEP lined PE tubing is best but @~$40/25ft roll +waiting for shipping vs $10/20ft roll on a drive to HD for the WATTS or free from others that have some kicking around, PE in general is fine for this industry.

Just a tid bit for the science geeks 

CO2 Permeability (cm2-cm Hg } x 10-10), 

silicone vs PE vs FEP 
20,132 vs 280 vs 5.9

HTH


----------



## Chris S

wtac said:


> Just a tid bit for the science geeks
> 
> CO2 Permeability (cm2-cm Hg } x 10-10),
> 
> silicone vs PE vs FEP
> 20,132 vs 280 vs 5.9
> 
> HTH


You, my friend, are a nerd!


----------



## Sunny

I am using the polyethyline tubing


----------



## Darkblade48

Do note that while the permeability of the silicone tubing is about 100 times more permeable than polyethylene tubing, the numbers quoted are raised to the negative tenth power...

I use silicone tubing for my pressurized CO2 setup and it is fine...


----------



## wtac

Hmmm...then by head I be scratching...LOL!


----------



## shadow_cruiser

From what I know, if the tank is setup right with the correct tubing, diffuser,etc a 10lb tank in a 55 gallon should last a year minimum.


----------

