Take a look at this wiki Home · segalion/raspipool Wiki · GitHub
Edit: the formula is in this code raspipool/fc.yaml at 1834e490b5a977efe0c389213b8ce8b69f3fa70f · segalion/raspipool · GitHub
Yeah had a look, cant see how a sensor was calculated for the FC?
Ahhh didnt look hard enough! Thanks see how i go understanding this
Hey, im just abit confused on how the 'input_number.e_fc_adjust works.
yes, so am I.
oh thank god! cause i ahve no idea what the estimate free chlorine, thats what this sensor is supposed to calculate
did you create the mean sensor for ORP or just use the live sensor?
The input number looks like an offset you would configure on the dashboard.
I haven’t yet, keeping a watching brief. However I’ll point you here RaspiPool. A DIY Swimming Pool Automation System and here RaspiPool (Pool Automation System with Raspberry pi + Home Assistant) | Page 2 | Trouble Free Pool. The latter forum has a lot of info (along with the contrary views of “experts”, just like every forum 
)
hey, sorry im not after the lovelace stuff. Thanks though
mmmm no straight answer tbh
You are not looking for lovelace stuff… that is where the input number is being setup.
just do the calculation in the earlier fc.yaml with a constant to replace the input number.
eg. the user using raspipool would input 78 on the dashboard.
so the input number would be 78%
so do you calc as
78 x orp x pH or whatever the calc is doing
but i dont know what the number is tbh?? thats whole point of this sensor i thought was to give me the Free Chlorine amount?
I can only think that it is some sort of “fudge factor”.
This looks great, but I thought ORP and consumer level PH sensors were notoriously unreliable… am I missing something?
You may well be right, but I would put the Atlas Scientific sensors somewhere above consumer level, they have pro ones, but that raises the price considerably.
I found this pH/Cl ppm/ORP conversion chart a while back. The original seems to have gone missing, but the wayback machine never forgets: https://web.archive.org/web/20180713135327if_/http://poolrx.com:80/wp-content/uploads/2013/07/PRx_pH-ORP_Conversion_Chart.pdf
As for the FC sensor - I plan to implement the calculation on the Arduino instead of in HA, and just have an MQTT topic that it will be sent to. That way the separation of concerns will allow someone to implement the Arduino side of the equation and use whatever system that can leverage MQTT on the other side.
Similar chart is here from one of the earlier links
https://github.com/segalion/raspipool/wiki/FC-vs-ORP-and-pH
Biggest problem with those charts is they only work in a strict pH range ~7-8pH. So outside of that it needs a different calc or an outside pH range(error) check. Presumably it’s because it’s some wild exponential calculation.
Yeah, but if your pH is below 7 or above 8 you’ve got bigger problems anyway. Water temperature also plays a part in the equation, apparently, but charts like these help get the concept.
Yeah water temp would influence it.
Been awhile since I’ve done any chemistry, most calculation standards are done at room temperature, so 20c or so, not sure if +/- 10c from that is going to be overly influential. Temperature is much more linear compared to the logarithmic pH.
There is probably redox(orp) rate calculation somewhere based on temp. TDS also potentially effects orp, more dissolved solids should increase your orp, but TDS isn’t limited to chlorine…