How to measaure dissolved CO2 without KH or pH related issues accuracy and over time

Tom Barr

Founder
Staff member
Administrator
Jan 23, 2005
18,696
747
113
I have been trying to figure out a good accurate method to measure CO2 for some time. I'd hoped for a device that was not influenced by KH, pH and associated errors/accuracy.

This product is useful as it also can log continuously over time at a variable interval to map trends in the dissolved CO2 concentration.

Note, this product is not cheap.

Dissolved CO2 Analyzer | Point Four Systems Inc.

But it does work well.
With an error of 2ppm, that's not bad over 0-60ppm.
10 min response time is not bad either.
The cost is though.


Regards,
Tom Barr
 

VaughnH

Lifetime Charter Member
Lifetime Member
Jan 24, 2005
3,011
94
48
85
Sacramento, CA
Now all we need to do is DIY it! Seriously, they don't give a price for this, so I assume you asked for and got a price? Would it be out of reach for a aquatic plants club?
 

creighton

Guru Class Expert
Jun 18, 2007
192
0
16
Is that simmilar to the type of system you did for the Esquire tank? Does anyone know the price?
 

Tom Barr

Founder
Staff member
Administrator
Jan 23, 2005
18,696
747
113
About 7,000$.

Hehe.

I can get it down and do some searching and get it to about 1500 or so.
About the same as a LDO for O2.

But I'm still looking, however, it does fit the needs for the hobby amazingly well.


Regards,
Tom Barr
 

VaughnH

Lifetime Charter Member
Lifetime Member
Jan 24, 2005
3,011
94
48
85
Sacramento, CA
So, if each of us in our club were to share the cost, it would only be: 7000/20 or a mere $350 each. But, if we had 200 members, it would be a reasonable $35 each. (That is called positive thinking.)

When the price of something is not shown on the advertising for it, you just have to know that that thing is not within the realm of possibility.

Sooo, Plan "B" is the DIY route.
 

ccLansman

Guru Class Expert
Jan 22, 2008
375
0
16
Vista, Ca
Any way to get a schematic from one of these companies? If so you could lay one of those bad boys out using sunstones free layout tool and they can fab the board for cheap. Then frys or radio shack the resistors, capacitors, probe ect...

I have a design project for a circuits class i am taking and would be interested in building one if you could find a layout of the system.

-Chris
 

VaughnH

Lifetime Charter Member
Lifetime Member
Jan 24, 2005
3,011
94
48
85
Sacramento, CA
To DIY something like this you would first have to understand the theory behind it. Only then could you figure out the sensing part, and finally, the electronics.
 

Tom Barr

Founder
Staff member
Administrator
Jan 23, 2005
18,696
747
113
Check out the reference to the development, via Tuft's University.

They also make a cheaper version in Canada for 2200$.
Bit cheaper, same thing though.

I'm getting one later.

Regards,
Tom barr