to be honest… after ordering the sensor I landed on that pump page… and I thought,’ if I can make a little box with on one side a valve (little flap of rubber) and on the other side the pump intake, I can control and refresh the air intake, that’s sometimes a problem with air quality sensors that are outside and in the open air… just for experimenting 
and maybe autotrigger then something like this
It‘s not possible to distinguish between CO and CO2 with this sensor
It measures CO2 and TVOC, nothing else, according the data sheets.
In a well „naturally“ ventilated sensor box it‘s not needed to actively blow through it (reduces power consumption)
Does anyone have recommendation on how to measure water level in a concrete water tank in a simple way?
Something like that:
I have seen quite a lot of projects, but nothing really appealing for my use case.
Best I have seen is with pressure sensors, but it is definitely not the easiest to put in place…
Most common are with distance sensors (ultrasonic), but I’m afraid it does not work well in humid environment…
sure, but I was not planning on battery operation.
I don’t know if you can distinquish bad and good air quality with this sensor as advertised… let’s find out
you need to know the exact level ?.. so a simple floating switch will not work for you ?
one for an almost empty tank and one for a full tank switching of the pump.
or non contact sensors
Not 100% exact, but a good approximation – I am not looking at ‘alerts’, but more real time monitoring of the level.
(‘real time’ in the LoRa spirit – like every hour or so)
These guys have a solution (ultrasonic based).
https://www.decentlab.com/products/ultrasonic-sensor
Not sure which sensor they are using
Edit:
Mmmmh…
Maybe this – not very cheap 
don’t know if you can build something yourself… but this is an interesting idea, just connect some electronics to it 
Yes, something with a float, and measuring in some way how far it goes might be an option…
… or I might decide to go for the MaxSonar. I just need one, and my tank is not easily accessible, so I would prefer to avoid too much trial and error with that 
Capacitive is nice for your aquarium, but doesn’t scale well for big tanks (2 meters and more) – It won’t be cheap either.
And simplest and cheapest if it could be done in advance (e.g. the tank would provide options for adding a level).
Just an idea:
In case of the concrete tank, maybe its possible to drill a hole on the top side to mount a tube that goes to the bottom side, can contain wires and sensor(s) and protect these from moist or other external influences.
With a sensitive (water)pressure sensor you could then measure the height of the water level based on the water pressure in the bottom of the tank.
FARNELL is behaving stupid again when you try to order a few modules (export restrictions blablabla) , so now i try my luck with MICROCHIP direct.
The RN2483A-I/RM103 is in stock, but the one with the 1.04 firmware is coming in June.
UPDATE have an account now @ microchip direct and bought with no problem a few modules
has anyone tried burning it? 1.0.4
Yes, that is an option as well. Note that you actually need a second one at the top to get the pressure difference.
Try to do measurement with ultrasonic sensor from Maxbotic with … is waterproof but is expensive
https://www.maxbotix.com/Arduino-Ultrasonic-Sensors-085/ and if u need low power mix with lmic library
One of the first jobs I had after leaving uni was to design something to control the water level in a reservour. I ended up using mulitple float switches at various heights on a mast which was sunk into the water. The switches were used in a system to control 3 water pumps. Hysteresis was there because of multiple floats!
It worked really well and it was easy to check (remote camera).
The main thing was that it had to be reliable, easy to install, visually check and service (if needed)
I know you want real time, but consider using floats to act as Event triggers - with a separate float in a separate circuit being used just for over/underfill checking
assembly programming to the max 
I assume that the tank is a pressure-less system. In that case a pressure sensor on the bottom should be sufficient to measure the absolute (‘static’) water pressure caused by the height of the water level.
The pressure caused by a water column of certain height is known and linear to its height. Therefore a single sensor on the bottom should be able to do the job.
The effect of difference in barometric (air) pressure between the bottom and the top of the tank is negligible in comparison to the water pressure (for very precise results one could include it in the calculation, but even then the effect of barometric pressure difference can also be treated as linear so any difference can be calculated, no need to measure it).
Yes, but you need to know the current barometric pressure. Variation of the weather conditions will influence your measurement.
I worked on the ‘think part’ of this problem and came up with some Time of flight approach using light beam. Similar to ultrasonic, but can be behind a window in a completely sealed enclosure.
It can be placed either on the top, or could be a floating device measuring up and down the levels.
