ph lowers increasing photoperiod and viceversa

[Ink]

Hello,
I've been into reefing since 1998. This is my 3rd tank, SPS dominated.
In every tank I had, I noticed an inverse relationship between photoperiod duration and ph.
If I increase light duration from 8hrs to 10hrs, I see that in some days interval, daily ph curve progressively lowers, reaching in the end a lower ph peak. Decreasing photoperiod, ph progressively increase.
My first tank was 50gal with 2x250w MH.
On the second one I tried 2x250MH, 2x400MH, 14x54w T5, 10x54w T5.
On this latter I tried photoperiod from 8h to 14h.
The actual one is 420 gal with 4 radion G3 pro and started few months ago.

this was my previous tank:
https://flic.kr/p/e3VoC2

In my new tank I'm trying to regulate my photoperiod according to corals health and then add fishes to balance DOM consumption with such a photoperiod.

Do someone has my same experience?
Do someone knows if we should care of this datum and manage our light according to this?

Thanks.

Luca

 

[Dan_P]

Have not experienced this nor read a post on this. What are the pH swings you are seeing?

 

[Ink]

Swing is into 0,1 - 0,2 range.

Luca

 

[Dan_P]

Swing is into 0,1 - 0,2 range.

Luca

That's fairly small. I wouldn't worry about it nor try to explain values that are close to the precision of the measurement. Let's see if anyone else sees a concern in these swings or has an explanation.

Dan

 

[sbreefer]

photo period can pull more or less CO2 from WC (carbonic acid) and by extension alter PH. not to worry. PH will fall during day and rise at night due to transpiration

 

[Ink]

I guess everybody would expect ph increases increasing photoperiod, not vice versa.

I do not worry about that, I'm trying to understand and improve my results.

IMO 0,2 points ph is an enormous difference and I can't expect it to derive from a measurement error.

Luca

 

[slief]

This would have nothing to do with your lighting unless its related to a photosynthetic bacteria that is consuming O2 during the photo period. My guess is that what you are seeing is the result of more Co2 in the room during the photo period because you or your homes inhabitants are probably in or near the room where the tank is during the light on period consuming more O2 and producing more Co2. If you are running a protein skimmer, get some nylon tubing and connect it to the skimmers air inlet. Route the tubing out a window so the skimmer can get fresh air from outside. If you Ph stabilizes, this would suggest your Ph issue is the result of higher Co2 levels in your tank room during that time of day.

 

[Ink]

slief, I've already checked for environmental CO2. Same person in the house at the same time.

All my familiy components gets out of home and come back at the same time and ph is higher than the previous days at the same time. I think this is sufficient to exclude environmental CO2 issue.

Luca

 

[slief]

How old is this system? If it's a new system, your tank is likely going through a barrage of bacterial cycles and that could be playing a role in what you are seeing.

 

[disc1]

IMO 0,2 points ph is an enormous difference and I can't expect it to derive from a measurement error.

Luca

Then you don't understand what pH is very well. That is a very tiny tiny difference that none of the inhabitants of your tank will notice.

On the reef out in nature the swings are often quite a bit larger than that from day to night.

 

[Ink]

disc1. your isn't an explanation.
I've always read that in nature swings are much smaller than in our tanks. I found in literature a range of 0,25 between day and night and seasons.
So I think 0,2 is a great number for me.

Slief, simply read what I wrote in the first message. 3 tanks in 15 years, independently from their age.

Luca

 

[slief]

disc1. your isn't an explanation.
I've always read that in nature swings are much smaller than in our tanks. I found in literature a range of 0,25 between day and night and seasons.
So I think 0,2 is a great number for me.

Slief, simply read what I wrote in the first message. 3 tanks in 15 years, independently from their age.

Luca

Your first line states:
"I've been into reefing since 1998. This is my 3rd tank, SPS dominated."

Towards the bottom you state:
"The actual one is 420 gal with 4 radion G3 pro and started few months ago"

I'm assuming your tank is only a few months old given the above. As such, your tank is going through all kinds of changes as well as bacterial cycles. These changes occur during the first several months or more after setting up an aquarium. My guess is that bacterial growth likely accounts for your Ph drops during the day as some bacteria competes for o2 in the system and photosynthetic bacteria could drop saturated o2 levels during light on hours causing a drop in Ph. As times goes on and the tank matures, things will stabilize.

 

[Ink]

this is my whole message, written above:

I've been into reefing since 1998. This is my 3rd tank, SPS dominated.
In every tank I had, I noticed an inverse relationship between photoperiod duration and ph.
If I increase light duration from 8hrs to 10hrs, I see that in some days interval, daily ph curve progressively lowers, reaching in the end a lower ph peak. Decreasing photoperiod, ph progressively increase.

Hard to understand it is referred to the last tank only. By the way polemic isn't the target of this topic, so please, let's talk about the topic.

My observation is referred and happened in any moment of any of the tank I've had, independently from their age. This exclude many confusing factors.

Luca