6 way CO2 System

[dmaister]

Hello everyone, I am trying to build a CO2 system to feed six tanks. This is more of a school experiment in which I am trying to control the pH of the water (to neutral) which has concrete specimens (limestone basically) that raise the pH of the water to around 11. I turn to you all because after a lot of reading I see that you are all experts in this type of system.

I am not looking for a high tech system, just help on parts and how to put all this together. I would like however a needle valve that is reliable and I wont have to be tweaking every hour, but that it wont hurt my pockets. All tanks will have the same amount of water and specimens so the behavior of the pH rise and drops should be about constant but I am contemplating if 6 needle valves are necessary or not. Also, what are some affordable options for bubble counters?

Thank you in advance, much appreciated!

 

[Gerryd]

Hi,

I think your two biggest challenges are:

1) Accuracy of the c02 delivered to EACH tank being EQUAL.

To do what you want you really need a manifold assembly and 6 needle valves (NV) one for each tank. But then how do you ensure they all deliver the same rate?

Or you can use ONE NV and feed to a simple AIR manifold they sell in the LFS for air pumps, but I am concered there as well to ensure a stable and equivalent rate.

2) Cost - you may need/use 6 NV, check valves (one for each NV), and brass connecting fittings based on how you decide to configure it.

I really think you need 6 NV to ensure better accuracy but still not sure how to ensure the SAME rate.

Better NV will provide better STABILITY in the rate than a less expensive one.

How do you intend to monitor/test the PH values? That's kind of important to the experiment, no? Just curious about it now


Use google advanced for just this site on 'manifold' and you will see what I mean.

Hope this helps.

 

[pepetj]

I have a 9 port manifold that works like a charm. I'm only using seven of the outputs. All go into ceramic glass diffusers (different models) and each one has a different length of hose.

I use a dual stage regulator (Concoa 212) adjusted at 20psi output and it's very easy to fine tune. Bettatail built this 9 port for me using a single solenoid and Japanese mini needle valves.

Pepetj
Santo Domingo

 

[Biollante]

In Water pH 8.4, CO2 is... Oh Well...

Hi,

I am not sure this is a serious inquiry, but on the off chance it is…

Six-way manifolds are common, if you are at all handy, not that difficult to do-it-yourself.

Any CO2 gas runs more than 2 feet (.60 cm) need reinforced or rigid tubing.

Reducing pH from 11 with CO2, I do not know, but I doubt you need expensive control valves, seems like a lot of CO2.

Anyway on the off chance you are serious:
http://www.bestaquariumregulator.com/CO2.html#manifold
http://www.aquacave.com/hexo-manifold-with-br6-individual-needle-valves-1160.html
http://www.myfishforum.com/aquarium...rs/4502-wts-multiple-outlet-co2-splitter.html
http://webpages.charter.net/cleochang/co2 regulator1_six2.jpg
http://webpages.charter.net/cleochang/co2 regulator1_six.jpg

Have fun…

Biollante

 

[bettatail]

Picture one is the official ADA product, the needle valve in the picture is actually a SMC AS2000 (or a AS3000) series needle valve. the SMC AS1000 series is smaller flow rate and better than the SMC AS2000.
The $288 speed controller.

SMC AS1000 series have smaller(better) flow rate at low turn range compare to Fabco NV-55.

This is what I build for pepeji, it is six way and nine way.

this is another picture, the top part is a six way, needle valves are SMC AS1000 series, made in Japan

 

[jaidexl]

I'm not sure what the objective of the experiment is but... if we say the parameters of each tank are exactly the same, that each limestone specimen affects each tank the same, then the only way one needle valve will work is if the delivery process is exactly the same. But there are always too many factors for this to work. If there is one line longer than the next, more or less restrictive for whatever reason, then gas will find the path of least resistance and one tank will be affected by gas more than the others. If you have one tank not dropping pH enough and try to increase gas to compensate, having only one valve to adjust will change the rate of gas to each tank and subsequently drop pH in all of them. If you need total control over pH in each tank independently then you will most likely need a dedicated valve and line for each. Currently the steadiest and most affordable needle valve is probably the Fabco NV55, to my knowledge, anyway. Or perhaps the one Bettatail mentioned but I do not have personal experience with that one.

 

[Gerryd]

Wait for a reply - no new posts

Hi all,

Please refrain from posting on this thread until the original poster (OP) responds with some type of acknowledgement.

I also have suspicions that this is not a genuine thread. But we will see. I apologize to the OP if it is real.

OP, please respond that this is a real request or not so folks don't waste their time with BS.

Thanks in advance.

 

[dmaister]

Hi thanks for the replies, busy weekend. I am interested in developing this project. To explain the project a little better, I am a civil engineer testing concrete specimens and heavy metal leaching. Leaching tests focus on submerging samples in a tank and testing for diffusion of the species of interest throughout time. pH is of concern because certain species leach more under certain pH's. I am trying to simulate a neutral pH in the tank ( the alkalinity of the concrete raises the pH of the unbuffered water). To do this I looked into how aquariums do it, and CO2 injections seems like it may work. I plan to measure the pH of the water every day, probably 4 times a day that is why I need something that is somewhat steady. The tanks should roughly maintain the pH around neutral, the one thing I want to avoid is HIGH pH swings like in the 9's and above. The overall project has 30 small tanks, but I believe I will be doing several CO2 tanks each with 6 way splitters. I've seen 12 way splitters but I dont know how well it may go. Any suggestions are welcomed. I am also thinking 6 needle valves (one in each line) is the way to go.

 

[bettatail]

To drop the PH from 11 to 7 you actually need a needle valve that provide constant low co2 flow, but not extremely low flow as in our application.
and I guess solenoid valve is not a necessary also.

www.clippard.com, you can get the manifold, or a custom order from them, they also have the needle valves, the MNV-1/2/3/4, they are all good for your application. we(planted tank hobbyists) only use MNV-3/4 for better bubble adjustment in the 2-5 bubble per second range.
hopefully this help

 

[dmaister]

Do any of you have experience using this 6 way splitter with needle valves? http://www.aquacave.com/hexo-manifold-with-br6-individual-needle-valves-1160.html Also what is an affordable regulator that I can use (I need 6 of these so cost could be an issue).

I was also reading some technical papers on people that have done something similar to what I am doing and they constantly bubbled CO2 into the water at ~15 psi and it maintained the pH around neutral. Any way I can use a regulator and hook it up to one of these http://www.amazon.com/dp/B002ZSIWUU/?tag=barrreport-21 ??

Thank you all for your help.

 

[jaidexl]

I've used needle valves like the ones in the first link, they're decent for our use and should work for what you're doing. The second link would work too if you're just bubbling CO2 with no need for control, those valves are just shut-offs. I have no idea how many ppm CO2 should be present to maintain a neutral pH in that situation, but you will save a lot of CO2 by misting with a ceramic or limewood diffuser versus bubbling it from open ended tubing. The smaller the bubbles the more efficient the diffusion, large bubbles rise up and leave before they are absorbed.

Now I am thinking, if one tank was set up with CO2 injection, and another with a continuous feed of reverse osmosis water, both to maintain neutral pH, would carbonic acid in tank 1 dissolve the concrete faster than tank 2?