InteliChem ORP & PH Readings

[snagytx81]

Hello,

I'm really new to IntelliChem, I have it only for 3 months, and I'm trying to really understand if the ORP fluctuation is really something that is expected or there is something wrong with the system/sensor. I'm not concerned about ORP accuracy compared to the correct value, but more if the trend makes sense or not.

I monitored the PH/ORP & Temp for the last 3 days - which are pretty much the same. This is are the graphs:



PH seems to be between 7.55 to 7.62 - while the target PH is 7.6 - I think this is pretty stable. I have a spa spillover which I think causes aeration and the PH to go up. During the monitoring span NO Chlorine was added.


Water temperature - seems to be accurate when I try to test with with another thermometer.


ORP fluctuates a lot - this is my concern 740mv to about 840mv - is this really normal ? I just had, 3 days ago, the sensor and wire replaced by a Pentair tech.

If I try to read the ORP with a cheap ORP reader I do see different values - which is expected in a way since the calibration might be different - but what concerns me is that throughout the day if I take ORP readings those readings are pretty within 20-30 mV.

Is IntelliChem Compensating for Temperature and/or PH ? Or Does UV have this much of an effect? Because of higher CYA I would expect the ORP to be a lot lower than it is. Would the CYA cause the fluctuation of ORP?

My readings are:
FC: 4.5(End)-5.0(start) - Taylor Kit (3 months old)
PH: as seen in the graph - confirmed with Taylor kit(3 months old)
TA: 70 ppm
CYA: 70 - I know it's high - pool builder dropped lots of tablets for the first 2 months - until IntelliChem was installed - not using tabs anymore.
CH: 425

 

[scottts]

Yes, your ORP will go down when the sun is on the pool and rise when it is dark. At least mine does.

 

[snagytx81]

Yes, your ORP will go down when the sun is on the pool and rise when it is dark. At least mine does.

Thanks Scottts - but does it fluctuate this much ? 100mv in one day .

 

[scottts]

That does seem like a lot given your CYA. There are a lot of factors to ORP though. Water temp, pH, how much your SWG runs for example.

Here's mine for the last few days. My CYA is currently 15 pH is 7.45 to 7.6. Water temp about 63.

 

[snagytx81]

My numbers are similar, PH & WaterTemp and the mV fluctuation is about 100mv - yours seems to be more stable about 35mv fluctuation. I don't use SWG - but liquid Chlorine. Yesterday I decided to partially replace water in the pool - I guess maybe 50% - which should bring me in the 30s with the CYA - over the "winter", if I can call it like that down here in the South, I suspect it will drop another 10-15 since I don't use tabs anymore.