Tropical Fish Forum

Tropical Fish Keeping => General Fishkeeping Chat => Topic started by: Helen on December 07, 2018, 08:35:31 AM

Title: Effect of photoperiod on pH
Post by: Helen on December 07, 2018, 08:35:31 AM
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.
Title: Re: Effect of photoperiod on pH
Post by: Sue on December 07, 2018, 08:56:54 AM
With live plants in your tank, this effect will be more pronounced than for someone with no live plants.



If anyone is interested in the chemistry of why the pH is affected, we can tell you  :)
Title: Re: Effect of photoperiod on pH
Post by: daveyng on December 10, 2018, 11:09:21 PM
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 ?
Title: Re: Effect of photoperiod on pH
Post by: Sue on December 11, 2018, 09:23:08 AM
If there was ammonia above trace level, this would be affected in the sense that more of it would be in the toxic ammonia form at higher pH. In a cycled tank or pond there should be no ammonia measurable with standard test kits but Helen's Seneye is much more sensitive so probably will be able to detect ammonia. What I don't know is whether Seneye can distinguish between ammonia and ammonium - @Helen over to you on this one  :)

Title: Re: Effect of photoperiod on pH
Post by: Helen on December 11, 2018, 04:24:08 PM
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)
Title: Re: Effect of photoperiod on pH
Post by: Sue on December 11, 2018, 04:30:46 PM
I think that @daveyng  also has a Seneye for his pond.  ;)

I'd forgotten that  :-[
Title: Re: Effect of photoperiod on pH
Post by: daveyng on December 11, 2018, 11:06:29 PM
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.
Title: Re: Effect of photoperiod on pH
Post by: Sue on December 12, 2018, 09:21:36 AM
The amount of hydrogen ions (ie pH) and any equilibrium in water eg ammonia-ammonium will be affected by changes in temperature, even just a degree or two. And that's just the chemistry part. Add plants and micro-organisms and they will also affect water chemistry. Plants taking up CO2 in the light, and more so in bright light, affects pH and the ammonia/ammonium ratio quite a lot.