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I am not as technically inclined as some members on here, but for those who are, answer me this. Could you not attach tubing to the end of this device where the sensor/probe is and run it into the aquarium in a similar fashion in which the drop checker works? Instead of waiting for a color change you could get an actual PPM reading? Please let me know if I am completely off base and why, or if this could possibly be a rudimentary way of getting more accurate co2 concentrations at a fraction of the cost of some high end equipment designed for submerged readings.
These sensors use NDIR to measure co2 in air, they aren't intended to run at 100% humidity which would be present in the tube and the condensation that would occur would distort the readings and possibly foul the sensor.
Commercial sensors for co2 under water still use the same sensors, but they have a membrane that allows gas transfer without moisture transfer which keeps the sensors accurate. They also have the sensors close to the membrane as a long tube would mean hours to get to equilibrium to get a real reading.
I was thinking more about this last night and one of those NDIR sensors along with a small resistive heater to prevent condensation in a small housing sealed with a ptfe filter would probably work.
I have too many projects on the go right now, but maybe down the line might be worth a try or if someone else wants to pick it up, happy to support where I can.
I was thinking more about this last night and one of those NDIR sensors along with a small resistive heater to prevent condensation in a small housing sealed with a ptfe filter would probably work.
I have too many projects on the go right now, but maybe down the line might be worth a try or if someone else wants to pick it up, happy to support where I can.
I like the idea, this may be a future project
The amount of trial and error would be huge though and finding a way to reliably calibrate would be tough without buying an expensive meter.
I like the idea, this may be a future project
The amount of trial and error would be huge though and finding a way to reliably calibrate would be tough without buying an expensive meter.
I didn’t think it was that simple. But if it was worth playing with to have something relatively reliable instead of thousands of dollars worth of equipment, I figured I’d float the idea.
I didn’t think it was that simple. But if it was worth playing with to have something relatively reliable instead of thousands of dollars worth of equipment, I figured I’d float the idea.
I didn’t think it was that simple. But if it was worth playing with to have something relatively reliable instead of thousands of dollars worth of equipment, I figured I’d float the idea.
The idea is very good. Unfortunately (and I quote from the link you provided): "The CO2 meter provides precise readings of carbon dioxide levels up to 9999ppm". The 10k ppm in air comes down to roughly 14 ppm in water...
The idea is very good. Unfortunately (and I quote from the link you provided): "The CO2 meter provides precise readings of carbon dioxide levels up to 9999ppm". The 10k ppm in air comes down to roughly 14 ppm in water...
Yes, the cheaper sensors are low range, we'd need a wider range sensor for our purposes which unfortunately drives up the cost significantly. These are mostly used for CO2 incubators, and other industrial applications. This one looks ideal, but priced at $281 CAD. 50k ppm range. Expensive to prototype with, especially if you spring a leak in the housing.
The GSS ExplorIR®-W is a low power, high performance sensor suited for battery operation in OEM portable instruments that need to measure up to 5% CO2 levels.
www.co2meter.com
This one has the same range, only $89 CAD, but the physical footprint is huge so that means larger air pocket, and much slower readings.
Unlock new possibilities in air quality monitoring with our 0-50000ppm CO2 sensor! Perfect for Arduino & Raspberry Pi. Fast response, high sensitivity!
I'm currently using a SCD41 module in my ESP32 hobby project:
It can go up to 40000 ppm (equivalent of 60 ppm in water) and roughly EUR 25,- when ordered in Asia.
I’ve use the sensor in my last post (the SCD41 module) connected to a ESP32-C3 supermini:
One can hook the sensor up with a QWIIC / Stemma QT cable:
3D printing (with water resistant PETG) a housing with some space for the sensor would result in something you can see on the right side:
The left wise is an airpocket with a 30mm fan connected to the ESP32. Glueing these two together resulting in the smallest digital dropchecker I've created so far. It measures 4 x 5 cm and 8 cm high (1.6'' x 2'' x 3.2''):
To be clear, only the bottom side is open, where the fan is for maximum diffusing rate. Put the bottom in the water and an air pocket is created:
CO2 will diffuse into the air/gas pocket, just like a regular drop checker. The actual difference is the co2 in the airpocket is not diffusing into the 4 dKH water with bromothymol blue pH reagent, but the CO2 in the air pocker is directly measured by the CO2 sensor.
I'm still testing this device on reaction speed of changing CO2 values in the water.
The ESP32 runs WiFi and a webserver to be able view all monitored data, currently on my low tech tank. It is able to push all data via MQTT along with some other functionalities:
If you like a full write up, please say so and I'll create one which I'm finished testing this one. Please tell me what you all want to read in such a write up.
Is the air movement from the fan to prevent condensation on the sensor? Is that working? Without an inlet or outlet, I'd be worried that the fan is just spinning in free air, but the heat from the fan motor might be enough to prevent condensation on the sensor.
Does your sensor track humidity as well? Would love to see if the fan prevents it from pegging to 100%. Would love more details.
Is the air movement from the fan to prevent condensation on the sensor? Is that working? Without an inlet or outlet, I'd be worried that the fan is just spinning in free air, but the heat from the fan motor might be enough to prevent condensation on the sensor.
Does your sensor track humidity as well? Would love to see if the fan prevents it from pegging to 100%. Would love more details.
The fan is for eliminating stagnant air in the gas chamber, so diffusion of CO2 between water and air is not hindered. The sensor itself is generating heat, it is 3 to 4 degrees Celsius warmer then its surroundings. This decreases chance of condensation in the sensor, as every *C decreases relative humidity by roughly 6%. I'm not logging humidity as I found it uninteresting data, but matches the explanation above as it currently roughly 80%:
The fan is for eliminating stagnant air in the gas chamber, so diffusion of CO2 between water and air is not hindered. The sensor itself is generating heat, it is 3 to 4 degrees Celsius warmer then its surroundings. This decreases chance of condensation in the sensor, as every *C decreases relative humidity by roughly 6%. I'm not logging humidity as I found it uninteresting data, but matches the explanation above as it currently roughly 80%: View attachment 21097
Currently I'm validating the measurements on a aerated tank, and comparing it against room measurements as I have a second sensor near the air pumps under the tank. After tests are succesfully finished I have planned to use it on it's designated purpose in my test tank (10 gallon) which has elevated CO2. By controlling CO2 level equipped with a third CO2 sensor in the airtight hood: link. But the hood needs some physical rework first.
Short answer: no graph available yet injecting CO2.
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