Display-Fuge light balance, pH and nuisance algae

[KonradTO]

Hi all,
just for some background: I have a 32g DT connected to a 15g sump/fuge full of macros and LR. No skimmer, few frags. Dinos (Amphidinium) problem atm.

I was just looking at the pH graph from the reef-pi and it got me thinking:
My highest point in pH (8) is right before DT lights start to ramp down, then it reaches the lowest point when my DT lights ramp up again (7.8).
I am wondering what is driving this. I have very few corals so this might be mainly coraline and nuisance algae consuming CO2 I suppose.
By adding more corals I should see a sharper increase in pH during the day right?
Also, my fuge is much more populated in CO2 consumers than my DT. Why do I have CO2 increasing at night then? Maybe because my fuge lights are less powerful than the ones in the DT, so most of the photosyntesis happens in the DT from nuisance algae?
This is about fine-tuning the nutrient export/CO2 consumption of the DT vs the FUGE. Maybe I am missing something, but I rarely read about this topic.
We basically have 2 systems interconnected that work at an inversed day cycle. Nuisance algae are more likely to "move" where the conditions are better so from this theoretically you could say that fuge lights must be always more intense than the DT lights?

If this makes sense it would mean that increasing light intensity in my fuge could 1) increase my pH minimum and 2) Stimulate nuisance algae to "displace" to my fuge instead of my dt. By measuring the nutrients during the day you would see what's left for corals in terms of nutrients after macros and single-cell algae in the fuge consumed most of it at night.

Very interesting topic I would like to know much more about.
What do you think about this?

 

[KonradTO]

 

[Dan_P]

Hi all,
just for some background: I have a 32g DT connected to a 15g sump/fuge full of macros and LR. No skimmer, few frags. Dinos (Amphidinium) problem atm.

I was just looking at the pH graph from the reef-pi and it got me thinking:
My highest point in pH (8) is right before DT lights start to ramp down, then it reaches the lowest point when my DT lights ramp up again (7.8).
I am wondering what is driving this. I have very few corals so this might be mainly coraline and nuisance algae consuming CO2 I suppose.
By adding more corals I should see a sharper increase in pH during the day right?
Also, my fuge is much more populated in CO2 consumers than my DT. Why do I have CO2 increasing at night then? Maybe because my fuge lights are less powerful than the ones in the DT, so most of the photosyntesis happens in the DT from nuisance algae?
This is about fine-tuning the nutrient export/CO2 consumption of the DT vs the FUGE. Maybe I am missing something, but I rarely read about this topic.
We basically have 2 systems interconnected that work at an inversed day cycle. Nuisance algae are more likely to "move" where the conditions are better so from this theoretically you could say that fuge lights must be always more intense than the DT lights?

If this makes sense it would mean that increasing light intensity in my fuge could 1) increase my pH minimum and 2) Stimulate nuisance algae to "displace" to my fuge instead of my dt. By measuring the nutrients during the day you would see what's left for corals in terms of nutrients after macros and single-cell algae in the fuge consumed most of it at night.

Very interesting topic I would like to know much more about.
What do you think about this?

It sounds right. Light intensity does drive photosynthesis and as long as there is enough nitrate and phosphate, can max out the growth rate with a high enougn intensity.

The algae does not migrate to brighter light but far more algae biomass will accumulate where the light is brighter.

Water flow can also plays an important role in how fast algae grow. Stagnant water can become depleted in CO2 and nutrients, slowing algae growth. Brighter lights and poor flow might not be as good for the algae as lower light intensity and good water movement.