Effect Of Photoperiod On PH

I am always interested in the detailed data my Seney gives me. In particular how the pH changes over a 24hr period. (This isn't something that could be seen with a liquid pH test)

My tank lights are on at 7:30 -1pm, 4:30 - 10pm.

Earlier in the week I put one of the lights on manual and forgot to turn it off for a couple days. I was starting to get a little worried why the pH wasn't coming down as normal. But it is really interesting to see how much of an effect that had on the pH.

I may revise my light regime to try and even out the photoperiods - it is on longer in the evening than the morning.

I had the same effect in the Pond over the summer. The pH shot up from about noon. (When direct sunlight) hit the water. I ended up covering it for a few hours each day to prevent this.
Did this also affect the NH3 levels ?

I think that @daveyng  also has a Seneye for his pond. 

My Seneye is currently showing NH3 as 0.016ppm. I've not trimmed the NH3 reading at all, so suspect this is more or less my tanks zero. NH3 reading generally doesn't seem to be affected by the pH. Though interestingly, with this slide I've had a couple blips where the NH3 has temporarily increased slightly. It reads in units of 0.002, so a blip up to 0.018 doesn't cause me concern.

My Seneye also gives a trace for NH4 in ppb. I think this is a calculated value, rather than a measured value. But because it is ppb, it is possible to see how it inversley mirrors the pH. (It has a clearer scale, so I occasionally refer to it to check the pH details)

My NH3 level in the Pond is currently at 0.012 ppm. NH4 averages out at 100 ppb with highs around 110 ppb and lows around 95 ppb. The pH is sitting around 7.4 at the moment. I’ve just changed the slide so it’s dropped a bit (from 7.48). My fault as I didn’t pre-soak the slide for a long enough period.
I know that when the temperature rises the NH4 level drops. I am assuming that it’s converting to NH3 when this happens.
The pH is extremely stable at the moment as the Pond temperature is only fluctuating by approximately 1 degree.