PH and lighting. An Experiment.

[FishTrader]

My hypothesis, since ph drops during the night, increasing the intensity of my lights during the day would increase ph.
My current setup is a 1yr old 65g AIO, mixed reef and fish. My corals stay alive, but do not flourish as I recall they did when I was previously in the hobby. I have been using a hybrid lighting and the schedule was 7am to 7pm LED that would ramp to mimic dusk to dawn. I would run t5 for only 1 hr, noon to 1. Chemical levels aside I would be testing 8.0ph consistently for the last few months on 2 separate red sea kits. This past week I increased the T5 lighting to 5 hrs and my ph has posted 8.4 2 days in a row.
I noted that an SPS which I had for a while lost some tissue and a torch and frogspawn seem fuller.
Fish are all fine.

 

[Gumbies R Us]

Following, I would be curious to see the results of this

 

[jda]

You would have to measure co2 in your home to know that was not the main driver. With the same co2 levels, it is possible that more of a full spectrum light source could drive are more complete photosynthesis than lights heavy in blue or just in the visible range.

There is a oceanic pH modeling tool that estimates pH based on a bunch of different stuff. It gives the photosynthetic bump on average about .2, but there are many other factors. I nearly any model, it is hard to be above .3 without chemical help. These are just models, though.

Don't rule out indoor co2. With weather not being as hot, a few hours with open windows can do much more to tank pH than people realize.

 

[FishTrader]

You would have to measure co2 in your home to know that was not the main driver. With the same co2 levels, it is possible that more of a full spectrum light source could drive are more complete photosynthesis than lights heavy in blue or just in the visible range.


Don't rule out indoor co2. With weather not being as hot, a few hours with open windows can do much more to tank pH than people realize.

Good point, but in this case the weather and window habits have been the same and the testing I perform weekly have been consistent. (Thanks to living in the PNW). I was going to send my RODI water to a lab bc I was beginning to suspect there was something in the water that was possibly acidic.
I'll update this thread with new data. I searched the forum here bc I know some reefers have the ph probes and was hoping to find any results of a correlation between lighting and ph.

 

[jda]

Indoor co2 monitor on Amazon are $50-60 and probably must to eliminate the largest possible influence. Get one with a cord since the batteries are all junk and barely last a day.

 

[rtparty]

Increasing PAR could, at least temporarily, slow down coral growth and them using CO2 in the water. Aka photosynthesis may slow. This could bump pH lower to begin with so watch for that as well

There are easier and more trusted ways to raise pH. Dosing kalkwasser being one of the easiest and cheapest.

But, if your PAR is too low, upping it will certainly be beneficial

 

[MnFish1]

If light alone is causing a pH rise, then turning the lights off or down for a couple days should cause the pH to drop back. It would be quite interesting if you had a constant pH meter rather than using the chemical tests

 

[jda]

You likely need 3 hobby grade pH meters for a good test - take 2 out of 3 readings. They just are not good enough to stand alone. If you got an industrial grade rig for pH, then one probably is fine.

 

[Randy Holmes-Farley]

Unless there is an effect such as rtparty mentions about a sudden increase in lighting stressing organisms, or if the lights already max out photosynthesis when they are on, i do not see how more photosynthesis from brighter lights or a longer light cycle could fail to raise pH, though whether it is significant and useful and detectably large against other factors, such as CO2 entry from the air is a different question.

 

[MnFish1]

Unless there is an effect such as rtparty mentions about a sudden increase in lighting stressing organisms, or if the lights already max out photosynthesis when they are on, i do not see how more photosynthesis from brighter lights or a longer light cycle could fail to raise pH, though whether it is significant and useful and detectably large against other factors, such as CO2 entry from the air is a different question.

However photosynthesis decreases CO2? Are you saying it would work with a change in lighting only temporarily until ambient air re-equalizes. It seems to me that it should lead to more active photosynthesis - and thus CO2 decrease - but that at night this should reverse. I am not sure the OP's 8.0--->8.4 is solely from light

 

[jda]

It is a cocktail. There is no guarantee that more light leads to more photosynthesis - increase, decrease or status quo can happen. In things with symbiotic zoox, you need more of certain kinds of light to move energy between photosystems to effectively scale, and the like. Not to get all nerdy on lighting, but some cut-spectrum lights like most LED have a max in output range where people get benefit whereas other larger spectrum lighting can provide much more of benefit.

Algae can grow faster and use more co2 in a fuge type of setting. More fuge and strong light has been liked to better pH either regular or reverse light cycle.

IME, and with the model, none of this can overcome high airborne co2 for long... which is not only an issue for our tanks in closed up homes, but also for the world moving forward as co2 is increasing.

 

[MnFish1]

It is a cocktail. There is no guarantee that more light leads to more photosynthesis - increase, decrease or status quo can happen. In things with symbiotic zoox, you need more of certain kinds of light to move energy between photosystems to effectively scale, and the like. Not to get all nerdy on lighting, but some cut-spectrum lights like most LED have a max in output range where people get benefit whereas other larger spectrum lighting can provide much more of benefit.

Algae can grow faster and use more co2 in a fuge type of setting. More fuge and strong light has been liked to better pH either regular or reverse light cycle.

IME, and with the model, none of this can overcome high airborne co2 for long... which is not only an issue for our tanks in closed up homes, but also for the world moving forward as co2 is increasing.

Thats the reason for the experiment, right? According to the OP - his pH increased from 8 to 8.4 with an increase in light. I'm not sure that this is correct - however - I can see theoretical reasons why it 'might' happen but hopefully more will be done.

 

[Randy Holmes-Farley]

However photosynthesis decreases CO2? Are you saying it would work with a change in lighting only temporarily until ambient air re-equalizes. It seems to me that it should lead to more active photosynthesis - and thus CO2 decrease - but that at night this should reverse. I am not sure the OP's 8.0--->8.4 is solely from light

If you strip out more CO2 during the day does not imply more released at night. The lower CO2 will linger into the night, but will decrease with each passing minute of aeration.

 

[Randy Holmes-Farley]

Thats the reason for the experiment, right? According to the OP - his pH increased from 8 to 8.4 with an increase in light. I'm not sure that this is correct - however - I can see theoretical reasons why it 'might' happen but hopefully more will be done.

Why wouldn’t it?

 

[MnFish1]

If you strip out more CO2 during the day does not imply more released at night. The lower CO2 will linger into the night, but will decrease with each passing minute of aeration.

Right

 

[MnFish1]

Why wouldn’t it?

Perhaps I'm confused - I thought people didn't believe his pH went from 8 ---- 8.4 due to a light change

 

[jda]

I don't think that it is likely, but I am not saying that it is impossible. If I knew the low number, then that would say more. If the tank went from 7.8 low to 8.0 high and then a week later was 7.8 low and 8.4 high, then that could be photosynthetic bump (and a big one) - the PS boost usually is all gone by morning in most cases. If the tank a week later was 8.1 low and 8.4 high, I look at room co2 or something else maybe along with a bit of PS boost since the low was higher.

If we knew the alk, temperature and room co2, I could put that into the model and it would estimate the non and PS pH levels.