ORP Problems?

[ufans]

What do you make of this graph?

No feeding or any additives are added except for normal feedings 1-2 times a day (normally only one feeding in the evening). Lights are on a normal 7am-7pm (ON) with a sump on reverse schedule.

I don't think that the ORP really changes that much. Don't know if it is a probe issue or a controller issue.

I am running a GLI Pro controller and an Ebay ORP probe. 1wire data transmission via a 4-20ma -> Dallas DS2450 chip. Logging is on a dedicated Linux (Ubuntu) running OWFS on a CRON job.

 

[Firewolf4]

From the Graph you've shown, it really doesn't look like a probe or controller issue. the A/D translation may be off but the pattern only shows irregularities during the day. Could it be possible that you're picking up noise from lights?
Only suggestion would be to get a stand alone ORP meter and when you see the ORP dropping out, measure it with the meter.
It's possible that with the onset of day you're getting more air movement which is throwing off the readings