How does running my refugium affect PH?

[DibsOnMcRibs]

Is there any reason, from a chemistry perspective, why I shouldn’t be running my refugium lighting 24/7?
My understanding is that during the day, plants uptake CO2, and release O2 overnight. To me this sounds like the reduced CO2 will increase my pH. It also sounds like my algae will be consuming waste twice as often compared to a normal lighting schedule. Yet, I always read about people, who know more than me, running their refugiums on a day and night schedule.
Am I missing something?

 

[P-Dub]

Is there any reason, from a chemistry perspective, why I shouldn’t be running my refugium lighting 24/7?
My understanding is that during the day, plants uptake CO2, and release O2 overnight. To me this sounds like the reduced CO2 will increase my pH. It also sounds like my algae will be consuming waste twice as often compared to a normal lighting schedule. Yet, I always read about people, who know more than me, running their refugiums on a day and night schedule.
Am I missing something?

Short answer-As with all things reef, stability is the key. The reason people run a day/night schedule, preferably reversed, with the refugium is to combat larger swings in pH. So you run the refugium lights at night to bring the pH up or maintain the pH that would normally swing down during lights out. If you run it 24/7 you are loosing the benefits of stability a reversed light schedule on the refugium provides.

 

[Montiman]

I don't know this is the case for algae, but it is true that many photosynthetic organisms perform cellular respiration at night and this is crucial for the long term health of the organism as certain functions are only performed while the organism respires. I have often wondered how relevant this is could be for our refugiums but I have not seen much research as to the importance of respiration in algae.

 

[magikfly]

I don't know about others, but I run a 80W grow lamp 24/7 over my fuge filled with chaeto. Haven't noticed anything Ph related and chaeto grows like weed.

 

[BeejReef]

Not chemistry, but biologically it's hard on the macro-algae to be lit 24/7. I'm no biologist, but have read many a thread where the OP cant keep chaeto alive bc it's lit all the time.

The corals photosynthesize and absorb carbon dioxide as well. They lower it during the day, the refugium lowers it at night. I'm not familiar with the biological respiration concerns you mention, but whether the corals and algae respire when lit, or when "sleeping," the going assumption is that having them offset aids in stability.

Some peeps with 24/7 Apex ph logs can show pretty convincing data that the fuge works pretty much as understood to.

 

[Jon Fishman]

I run my ATS 24/7 out of laziness and the “swings” are very subtle