pH & Photosynthesis Correlation

[spsick]

Wondering what conclusion I can draw from this.

I run a 6 bulb T5 fixture.
-2 bulbs 11 hours
-other 4 bulbs 6 hours peak

My pH dips the second the peak period is over. Can I assume photosynthesis stops at this point? Should I run all bulbs longer and a shorter total period?

 

[Timfish]

You're probably also seeing daily variation due to weather and how frequently outside doors are opened and closed during the day might show up also. Photosynthesis isn't stopping and might not even be slowing down (although that might seem reasonable) and I wouldn't alter the lighting schedule just to see a broader curve. Knowing when the lights turn on and off in relation ship to the chart would be helpful. For example, there's a small plateau just after the pH starts to rise and another small plateau at the end that look to be the same, is it indicating when the first set of 2 bulbs turn on? If so why isn't there something similar when the set of 4 bulbs turn on? Since corals can reach a saturation point and photosynthesis levels off when this happens is it possible the second set of 4 bulbs is providing more light than is useful for the corals and is only forcing the corals in this system to make more fluorescing and chromo proteins to deal with the excess light? Or are we just heading down a rabbit hole?

 

[spsick]

Rabbit hole indeed! I edited the photo to show where bulbs go on and off. I have a fresh air line to my skimmer and since then open windows and people home/at work have zero impact on my pH so that’s what got me thinking about photosynthesis.

 

[Timfish]

I want to emphasize this guess work. It looks like the two small plateaus are indicative of pH levels from photosynthesis with just the 2 bulbs on. Photosythesis probably plateaus some where before pH hits it peak and what you're seeing is the continuing draw down of CO2 and increase in oxygen influencing pH.

To get a better idea of the rleationship between your lighting and pH you might try running the system for 3 days with only the 2 bulbs turning on thier normal photoperiod. Then run it 3 days with normal lighting schedule with all 6 bulbs. Then run the system with just the 4 bulbs on for thier normal 6 hours for three days.

 

[spsick]

I want to emphasize this guess work. It looks like the two small plateaus are indicative of pH levels from photosynthesis with just the 2 bulbs on. Photosythesis probably plateaus some where before pH hits it peak and what you're seeing is the continuing draw down of CO2 and increase in oxygen influencing pH.

To get a better idea of the rleationship between your lighting and pH you might try running the system for 3 days with only the 2 bulbs turning on thier normal photoperiod. Then run it 3 days with normal lighting schedule with all 6 bulbs. Then run the system with just the 4 bulbs on for thier normal 6 hours for three days.

Great suggestion, thanks!

 

[GARRIGA]

I want to emphasize this guess work. It looks like the two small plateaus are indicative of pH levels from photosynthesis with just the 2 bulbs on. Photosythesis probably plateaus some where before pH hits it peak and what you're seeing is the continuing draw down of CO2 and increase in oxygen influencing pH.

To get a better idea of the rleationship between your lighting and pH you might try running the system for 3 days with only the 2 bulbs turning on thier normal photoperiod. Then run it 3 days with normal lighting schedule with all 6 bulbs. Then run the system with just the 4 bulbs on for thier normal 6 hours for three days.

Only way to solve a problem is test different hypothesis.

 

[spsick]

Update:

All bulbs on period to 7 hours and found my pH swing to not change a ton but there is more time in the 8.2-8.4 range so it brought up the average a bit. Also observed growth picked up most noticeably on my various staghorns so I’ll call it a win. I suppose I should try another hour for humor.