History Graph for pH MQTT

Hello,
I’m pretty new to HA and curently I try to get the pH Value of my Aquarium into HA to create a pH controller via automation.
The automation and the MQTT part are working fine.

Current goal is to show the pH value as History graph, maybe together with the relay state of the CO2 relay.

I’ve created following MQTT sensor and I get suffent values for pH.

- platform: mqtt
    name: "Nano PH"
    state_topic: "NanoAquarium/ph"
    qos: 0
    unit_of_measurement: "pH"  //tried PH & ph as well

But it looks like that HA interpret the value still as discret instead of continuos, because the bar graph show up in the History Graph in lovelace.

If I change the unit_of_measurement from “pH” to “°C” the histroy graph it tranformed to an °C/time graph (but measuring in °C is not correct here …).

What can I do to show a pH/time diagram in an history graph ?
And is there a list of supported Unit’s for “unit_of_measurement” availible ? I couldn’t find anything.

Thanks

Get it done,
there are “NaN” values stored for the value in the past. Thats why a History Graph didn’t show up.

Do you mean using “PH” as the unit_of_measurement ended up working? Or did you stick with “°C”? Or nothing at all?