Algae Scrubber/Refugium PH Swing Chemistry???

[gb530]

I have an algae scrubber running on my tank and yesterday I cleaned the screen. I removed the algae on both sides. This morning I woke up and my pH was reading at 7.79! My pH is typically right around 8.2.

My question. Could the removal of the algae on the scrubber affect the pH that much? What causes pH to swing when the lights are on/off?

I know people say run your refugium at night to lessen pH swings, and I have listened but I don't really know the chemistry behind it and why it swings.

Any input is appreciated!

 

[gb530]

I would also like to note that my pH is back to 8.02 right now. It's 1:48pm here and my lights turn to 100% at noon.

 

[disc1]

7.8 is nothing to fret over. No telling what caused it but I wouldn't stress too much.

What drives pH in relation to lights is CO2. CO2 acts as an acid in the water driving pH down. As your animals respire, they are breathing out more CO2 and pushing pH down. Meanwhile the photosynthetic creatures like corals and algae are sucking up CO2 while the lights are on pushing pH down. When the lights are off the photosynthetic things are respiring like everyone else and giving off more CO2.

 

[Randy Holmes-Farley]

Unless there is some reason to not do so, I'd either light the refugium on a reverse light cycle, or keep it lit 24/7. I've doen both. At the moment it is a reverse cycle.

Cleaning the screen might have released substantial organic matter that might drop pH a bit. You also lessened the boost in pH that the refugium was giving since it may not be photosynthesizing as much right after cleaning.

 

[gb530]

7.8 is nothing to fret over. No telling what caused it but I wouldn't stress too much.

What drives pH in relation to lights is CO2. CO2 acts as an acid in the water driving pH down. As your animals respire, they are breathing out more CO2 and pushing pH down. Meanwhile the photosynthetic creatures like corals and algae are sucking up CO2 while the lights are on pushing pH down. When the lights are off the photosynthetic things are respiring like everyone else and giving off more CO2.

Okayyy, I was a little worried there with the swing. Thanks!

 

[gb530]

Unless there is some reason to not do so, I'd either light the refugium on a reverse light cycle, or keep it lit 24/7. I've doen both. At the moment it is a reverse cycle.

Cleaning the screen might have released substantial organic matter that might drop pH a bit. You also lessened the boost in pH that the refugium was giving since it may not be photosynthesizing as much right after cleaning.

I have it reverse but the refugium is off two hours after the lights turn on and 2 hours before the lights turns off. So the light on the refugium is on for 4 hours total when the main tank light is on.

As for the screen, I rinse it off well with the hose before hooking it back up.

Thanks for your input Randy!

 

[Randy Holmes-Farley]

You're welcome.

Happy Reefing.

 

[gb530]

7.8 is nothing to fret over. No telling what caused it but I wouldn't stress too much.

What drives pH in relation to lights is CO2. CO2 acts as an acid in the water driving pH down. As your animals respire, they are breathing out more CO2 and pushing pH down. Meanwhile the photosynthetic creatures like corals and algae are sucking up CO2 while the lights are on pushing pH down. When the lights are off the photosynthetic things are respiring like everyone else and giving off more CO2.

So when the lights are off pH is dropping, when the lights are on pH increases?

 

[FlyPenFly]

Cleaning the screen might have released substantial organic matter that might drop pH a bit.

Interesting, organic deterius would lower pH?

 

[bertoni]

A lot of decay byproducts are organic acids, which is one reason a cycling tank tends to have a lot pH.

 

[Randy Holmes-Farley]

Not just detritus. The broken macroalgae stems may ooze organic matter until they seal themselves.