# Splitting CO2 into 2 tanks



## Heady (Mar 4, 2003)

I have a Milwaukee 957 regulator feeding CO2 to a 100 gallon planted tank. Is there some way to feed some of this CO2 to a 29 gallon tank that's about 10 feet away?


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## houseofcards (Feb 16, 2005)

For that to work correctly, you need a splitter like this:

http://cgi.ebay.com/2-way-Brass-Co2-splitter-for-solenoid-gauge-regulator_W0QQitemZ250240714882QQihZ015QQcategoryZ66794QQrdZ1QQssPageNameZWD1VQQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247


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## Robert Hudson (Feb 5, 2004)

The only problem with that is you have to remove the existing needle valve bubble counter from the milwaukee regulator and re place it with the dual one. That will void your Milwaukee warranty. If its out of warranty, I guess it doesn't matter. You get the same crappy needle valve, two instead of one.

Another alternative is to use an inline splitter, a T valve, and then have an inline needle valve on each line. You would have to add a bubble counter on each line too. An inline splitter is cheap, 2 or 3 dollars. An inline needle valve could be anywhere from 12 to 25 dollars depending on what brand you get. It would be a big step up from the Milwaukee needle valve. You can get a very inexpensive inline bubble counter. You would keep the needle valve on the regulator wide open and then use the inline valves to ajust the flow independently on each line. I have all these things if you are interested.


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## mikenas102 (Feb 8, 2006)

If you go with an inline needle valve I suggest the Fabco. They are excellent.


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## reybie (Jul 18, 2007)

I used the same one houseofcards linked to except without the bubble counter. I used a ghetto bubble counter instead, my other tank was about 30 feet away (hose wise). Tip, it takes a few minutes for the tubing to pressurize the longer it gets.


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## houseofcards (Feb 16, 2005)

Personally I have found using a T-Bar to be unreliable. As the co2 takes the path of least resistance. Adding inline needlevalves as well as bubble counters creates more failure points and you might as well buy a new regulator already after adding up the costs.


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## orlando (Feb 14, 2007)

*Our Manifold....Pics*

From trial and error, here is what I find works best.


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## Robert Hudson (Feb 5, 2004)

Well thats the same thing as what House of cards linked to. Another alternative is an inline MANIFOLD. A manifold is a bank of needle valves.

Like this










These are highly sensitive needle valves somewhere between the Clippard and the Fabco. It's available with 2 needle valves all the way up to 8.

Here is another type of manifold called the HEX










It has six independent needle valves and can connect either inline or threaded onto the regulator.

You can also buy manifolds in pieces from Rex Grigg










This is a four port manifold, (three ports for needle valves, one port for inline hose barb) You would need to add the hose barb and needle valves


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## Zapins (Jul 28, 2004)

They also make plastic cheap manifolds for splitting air from an air pump to multiple tanks. You could use one of these for the CO2 line. You can find them at nearly every pet store right next to the air pumps and silicon tubing.

You will be losing a lot of CO2 through the tubing unless the tube is made from copper or CO2 resistant material. I remember reading silicon tubes let up to 30% of the gas traveling through them PER FOOT to escape through the walls of the tube.


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## orlando (Feb 14, 2007)

Zapins said:


> They also make plastic cheap manifolds for splitting air from an air pump to multiple tanks. You could use one of these for the CO2 line. You can find them at nearly every pet store right next to the air pumps and silicon tubing.
> 
> You will be losing a lot of CO2 through the tubing unless the tube is made from copper or CO2 resistant material. I remember reading silicon tubes let up to 30% of the gas traveling through them PER FOOT to escape through the walls of the tube.


Your correct Zapins on tubing. In line manifolds are more likely to leak co2 due to more connections that can be easily eliminated by attaching a manifold directly to your solenoid.


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## Robert Hudson (Feb 5, 2004)

> They also make plastic cheap manifolds for splitting air from an air pump to multiple tanks. You could use one of these for the CO2 line.


They are not air tight, they leak gas like a sive... really bad. I tried to seal one with silicone and I could not get it to work. I went thru a ten pound C02 cannister in 5 days! Its too bad, because they are really cheap


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## hoppycalif (Apr 7, 2005)

I have a lot of doubts about whether one foot of silicon tubing loses 30% of the CO2 in it. That means a 7 foot length loses more than 90% of the CO2. If this were really true a coil of that silicon tubing would be a great CO2 diffuser in our tanks. But, I have yet to see anyone using it for that. The ideal way to use it might be to coil the tubing in a DIY inline CO2 reactor per the DIY sticky. Has anyone heard of this being done successfully?


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## houseofcards (Feb 16, 2005)

hoppycalif said:


> I have a lot of doubts about whether one foot of silicon tubing loses 30% of the CO2 in it. That means a 7 foot length loses more than 90% of the CO2. If this were really true a coil of that silicon tubing would be a great CO2 diffuser in our tanks. But, I have yet to see anyone using it for that. The ideal way to use it might be to coil the tubing in a DIY inline lCO2 reactor per the DIY sticky. Has anyone heard of this being done successfully?


I doubt that as well. Not to say some co2 doesn't diffuse but the math doesn't add up. Personally I have some tanks running with co2 tubing others with the cheap stuff (Lee's tubing) from LFS and I honestly can't tell much of a difference between how long my cylinders last.

The reason I recommend that splitter in my first post is because I do think you run the risk of more problems by attaching a bunch of items inline vs a direct connection to the regulator.


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## Brooklyn Plant Guy (May 23, 2008)

I have been using an inline manifold like the one Robert Hudson is talking about. In fact, if I remember correctly I got it from him. It is running six aquariums off of a single CO2 cylinder. I am using the correct tubing. In each tank I am using the diffuser made by Red Sea which have their own bubble counters built in. I have been very happy with the results.


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## Zapins (Jul 28, 2004)

houseofcards the maths does add up 

If you start out with 100 cubic feet of gas and lose 30% of the gas that passes through each foot then after one foot you have 70 cubic feet of gas, now you lose another 30% of the gas that goes through the next foot, 70 cubic * .3 = 49 cubic feet left. Now you lose 30% of this gas, so, 49 cubic feet times .3 = 34.3 cubic feet left, and so on until the amount of gas at the end is essentially 0 (at about 12 feet from the tank).

The amount of gas that leaks through the silicon tubing definitely depends on the amount of back pressure at the open end. So if the tube runs for 6 feet straight down in the water to a diffuser, the 6 feet of water would make it very hard for gas bubbles to make it to the open end underwater. The pressure would cause more than 30% / foot to escape since its easier for the gas to escape through the silicon walls than overcome 6 feet of water pressure.


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## hoppycalif (Apr 7, 2005)

I once put a couple of feet of silicone tubing in my tank, with the open end connected to whatever I was using for a diffuser then. I watched the tubing for quite awhile looking for bubbles, but none appeared. So, if any leaked in that length of tubing it went directly into solution in the water, which is great. I didn't have to change my bubble rate to get whatever amount I was used to from my diffuser. That suggested to me that the loss from that tubing wasn't at all great.


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## Mud Pie Mama (Jul 30, 2006)

*Re: Our Manifold....Pics*



orlando said:


> From trial and error, here is what I find works best.


This is just what I've been trying to figure out for a group of three tanks I have.

I see you mention to attach this manifold/needle valve/bubble counter to the solenoid. Is there a way to attach it directly to the regulator and not use a solenoid? I'm thinking of trying the PPS-pro fertilization and run the gas at lower levels and 24/7, as Edward recommends. Would there be any problems with omitting the solenoid?

TIA!


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## orlando (Feb 14, 2007)

*Re: Our Manifold....Pics*



Mud Pie Mama said:


> This is just what I've been trying to figure out for a group of three tanks I have.
> 
> I see you mention to attach this manifold/needle valve/bubble counter to the solenoid. Is there a way to attach it directly to the regulator and not use a solenoid? I'm thinking of trying the PPS-pro fertilization and run the gas at lower levels and 24/7, as Edward recommends. Would there be any problems with omitting the solenoid?
> 
> TIA!


Yes, you can do that no problem. It would just require a few fittings.


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## Robert Hudson (Feb 5, 2004)

> The amount of gas that leaks through the silicon tubing definitely depends on the amount of back pressure at the open end. So if the tube runs for 6 feet straight down in the water to a diffuser, the 6 feet of water would make it very hard for gas bubbles to make it to the open end underwater. The pressure would cause more than 30% / foot to escape since its easier for the gas to escape through the silicon walls than overcome 6 feet of water pressure.


I don't know how you could possibly figure that, but I won't argue the point. The amount of gas that seeps through silicone tubing is miniscule. Less than 1%. If it was any more than that, it would be like a leak. At 30% you would hear a hissing sound, and your C02 tank would be empty in an hour.

I have run tubing for 20 feet or more. I always use polyeurathane tubing which has been the common tubing people have called "C02 tubing".

Any type of manifold or splitting a line, requires more pressure, and tinkering. The more lines, the more tinkering. Its does not matter if the manifold is connected directly to the regulator, or in line. It still requires an ajustment of pressure and operates EXACTLY the same. An inline manifold is just as safe to use as one connected to the regulator. The only difference is an inline manifold is much easier to connect...you just plug in the tubing and you are done. No stripping of screws or sockets, no danger of breaking anything, or applyig to much tork, no teflon tape, or sealers, or whatever. There is a buma rubber seal around the hose barb all ready. The barbs are triple edged and hold the tubing so tightly you have to cut it off to remove it. You can have a solenoid in front of the manifold, even inline that will shut off the whole system. You can by pass a solenoid without removing it. Just leave it plugged in all the time so the valve is always open. Thats how a solenoid works. When it recieves power, (plugged into an electrical socket) the valve is open allowing the gas to pass thru. When it recieves no power, the valve is closed.


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## Zapins (Jul 28, 2004)

http://fins.actwin.com/aquatic-plants/month.200111/msg00503.html

Look through this link for calculations (summarized below) on rates of CO2 loss through thick and thin silicon tubing, all according to Fick's law (which is essentially an equation that allows one to calculate the percentage of gas lost through a membrane [silicon tubing]).

Percent CO2 loss (if aquarium use is continuous 1 bubble (0.06 cc) per
sec**)

Tube length------thin wall, HP---Thick wall, HP----Thick wall, LP
1 ft--------------22%--------------9-----------------5
2----------------37----------------16----------------9
4----------------54----------------28----------------17
8----------------70----------------43----------------28
10---------------74----------------49----------------33

HP means high pressure calculated at 15.0 psi (77.6 cm-Hg) and LP means low pressure calculated at 1.0 psi (5.1 cm-Hg). Additionally, we all use thin wall tubing defined as 3/16" inside diameter (ID).

Additional measurements can be found at:
http://www.coleparmer.com/techinfo/techinfo.asp?htmlfile=SelectingTubing.htm

You wouldn't hear a hissing sound at 30% loss, because you are losing 30% of the GAS that flows THROUGH the co2 tube. The small pores along the tube are microscopic and produce no audible noise. A hissing would be heard only from point sources like fittings etc... not from the entire length of the tube.

At 1 bubble per second, you lose 22% of that bubble per second for 1 foot of silicon tubing and you will lose 74% of that bubble per second over a 10 foot stretch of silicon tubing (see chart above).

Silicon tubing does leak a significant amount of gas through the walls of the tubing. There is no denying it. If you are ok with losing up to 30% of the CO2 tank over time, then thats all well and good. I sometimes run a silicon tubing as well instead of the CO2 resistant polyeurathane tubing which I prefer using, simply because I don't care about spending the money to refill my canister a few months sooner than I would have using the correct stuff.

I urge everyone who is interested to do a bit more research on the subject before deciding on the kind of tubing they want to use - that is if you want to save some money in the long run (might not be on everyone's priority list though).


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## sonaps (Nov 15, 2005)

At the bottom of the above reference is written: **The percent loss is a function of use rate. For example, if you use 5 bubbles per second at LP with 4 ft of tubing, your loss rate would be only 4%. 

This is probably why most don’t notice a significant loss, because of higher use than 1 bubble per second. I think it would be interesting to tie a knot in the end of a long silicone tube and connect it to my CO2 supply. I would be interested to see how many bubbles would actually go through my bubble counter. If the loss is as large as many are saying than I should be able to see the bubbles come up fairly quickly.


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## Zapins (Jul 28, 2004)

That is at low pressure of 1 psi, our tanks run at high pressure, usually more than 15 psi so our losses are at the very minimum 22% for 1 foot.

I suppose the 1 psi calculation is much closer to the values that would be achieved with DIY gas and the 15 psi pressure calculations closer to the values seen in pressurized CO2 systems.


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## hoppycalif (Apr 7, 2005)

Zapins said:


> That is at low pressure of 1 psi, our tanks run at high pressure, usually more than 15 psi so our losses are at the very minimum 22% for 1 foot.
> 
> I suppose the 1 psi calculation is much closer to the values that would be achieved with DIY gas and the 15 psi pressure calculations closer to the values seen in pressurized CO2 systems.


The pressure downstream of the needle valve is likely to be only one or two psi, whatever it takes to hold a check valve open, and force CO2 through the diffuser. I doubt that many of us have plastic tubing between the regulator and needle valve. I think that is why we get by so well using what should be terrible tubing material for CO2 lines.


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## Zapins (Jul 28, 2004)

Hmmm good point. Still there is quite a bit of leakage even at low pressure!


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## Zapins (Jul 28, 2004)

Just thought I'd post an update on some interesting new information that I just found out by doing some tests with my regulator and researching a bit online.

I just did a test on one of my CO2 regulators to check the downstream pressure and it turns out the PSI of the needle valve is nearly exactly 15 psi.

I found this out by using my duel gauge Milwaukee regulator and looking at the second dial that shows psi in the regulator itself (not the tank psi). I closed the needle valve and opened the regulator valve setting the pressure at 35 psi. Then I slowly opened the needle valve until 1-2 bubbles per second were coming out. Then I looked at the pressure of the regulator and it was 20 psi. The difference gives 15 psi - the pressure of the gas leaving the needle valve.

****Note**** the psi of the gas leaving the needle valve is 15 psi, which makes sense since a canister filter runs at more than 1 psi, and I have my CO2 tube running into an inline reactor. This means that the pressure of the CO2 gas coming into the system must be greater than the canister filter psi or the gas simple would not enter the tubing, in fact the water would enter the needle valve if the pressure wasn't more than the canister filter pressure. To enter the canister filter at a good flow rate of 1 bubble or more per second the pressure would have to be significantly higher than 1 psi or the gas wouldn't flow into the water that fast.

A quick check online confirms that the average pressure of the gas leaving the needle valve is about 15 psi. To quote the site:



Website said:


> What's the difference between high pressure and low pressure systems?
> A low pressure system runs about 1 psi, a high pressure system about 15 psi. A low pressure system is hard to regulate. The regulator will regulate well from about 10-25 psi. A low pressure system needs a way to drop the 10 psi to 1 psi. Usually a needle valve is used, but this is not very reliable, since a needle valve is not designed to regulate pressure, but flow. If you set the regulator very low, the pressure will wander up and down. If you set the needle valve almost closed (as you must to make a big pressure drop) the flow rate will vary a lot.
> The right way to do low pressure is to daisy-chain a carbon dioxide regulator and a natural gas regulator. But that is expensive and untried "experimental" territory. If you must have a low pressure system it is the way to go. We can help with it. Bring your wallet or charge card, though.


Additionally, I found out that the needle valve does not control the pressure, it just controls the flow rate (read the site below).

Or if you want to read the article the part about low and high pressure it is discussed at the top (where it says you need 2 regulators in a line) and in further detail 2/3rds of the way down the page.
http://www.wcf.com/co2iron/faq.html

So, based on this information we are all running "high pressure" systems whether or not we inject directly into the canister filter line or inject the CO2 into a powerhead or some other kind of diffuser, its all at roughly 15 psi. This essentially means all the calculations I posted before and all the CO2 lost through the silicon tubing is correct.


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## sonaps (Nov 15, 2005)

Zapins said:


> So, based on this information we are all running "high pressure" systems whether or not we inject directly into the canister filter line or inject the CO2 into a powerhead or some other kind of diffuser, its all at roughly 15 psi. This essentially means all the calculations I posted before and all the CO2 lost through the silicon tubing is correct.


I'm going to have to disagree. Just because you release 15 psi from behind the needle valve that does not translate into 15 psi being on the other side of the needle valve. If that reasoning were true then I could argue that if I crank up the low pressure side of my regulator to 60 psi and then opened my needle valve all the way that I now have 60 psi in my line. If there is little to no back pressure in a line after a needle valve - like when putting the line into the intake of a power head; there is no way to have 15 psi in the line. Another fact is that I can blow air into my inline reactor while the pump is running water through it. Since human lungs can only produce about 2 psi maximum, (and I don't have to blow that hard) we can clearly see that it takes less than 2 psi to push CO2 into my (and probably most all) inline reactors.


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## hoppycalif (Apr 7, 2005)

Sonaps is correct. The only thing that determines the pressure downstream of the needle valve is the restriction in that line from that point onward. If we actually had 15 psi in that line at the needle valve, CO2 would blast out of the other end unless we had a restriction there, like another needle valve, which we don't have, or a diffuser, which we may have.

Cannister filters produce an outlet pressure that is also determined by the restrictions in the filter return line. Among those restrictions are the weight of the water above the filter, usually 3 feet or less, which is about 1.5 psi, the restriction caused by elbows, tubing, a reactor, a heater, etc. This pressure will be as high as it takes to get the water up to the tank, until you reach the maximum pressure the cannister filter pump can produce, and that is generally only about 4 or 5 feet of water or between 2 and 2.5 psi approximately.

So, it only takes a CO2 pressure of about 2 psi to get CO2 into the return filter line. Any higher pressure and you get a blast of CO2 into that line. Bubbles per second represent an extremely low flow rate, so low there is no measurable pressure loss in the CO2 tubing until you get to really long runs of tubing.


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