Do Corals Consume Alkalinity When the Lights Are Off?

[SPS Reefer]

Hello everyone,

I was thinking about doing my calcium and alkalinity testing at night and dosing as needed but I wanted to dose my alkalinity in the morning. Would the alkalinity value change from when I turn the lights off to when they come on in the morning and is this a significant change that my dosage should be adjusted? o_O

Thank you and happy reefing!!

 

[Scorpius]

No one really knows. Different studies go either way. I would say a reduction in alkalinity and calcium consumption at night due to lack of photosynthesis, but it's just a guess.

 

[BluTang85]

I have heard that corals in the ocean extract there long tentacles to capture critters that are floating buy. during the day they collect photosynthesis. After taking multiple tests with red sea for DKH i have seen in my results that its lower come morning once the lights just turn on then at night when they turn off. so i dose more during the night time then during the day when the lights are on.

 

[ajcanale]

Yes, assuming conditions are favorable, stony corals will grow at night, therefore will consume calcium and carbonate alkalinity.

 

[LobsterOfJustice]

Now that alkalinity monitors are available we are starting to get insight into daily demand. After a few weeks of hourly testing, I was able to see that my tank uses most of its alkalinity from a few hours before lights out until a few hours after lights out. There is zero consumption from about midnight to 7am. I believe others have noticed that most of their consumption is towards the end of the photo period as well.

 

[taricha]

I was able to see that my tank uses most of its alkalinity from a few hours before lights out until a few hours after lights out. There is zero consumption from about midnight to 7am. I believe others have noticed that most of their consumption is towards the end of the photo period as well.

So it tracks kinda like pH, but maybe a little behind it? Interesting.

 

[SPS Reefer]

Now that alkalinity monitors are available we are starting to get insight into daily demand. After a few weeks of hourly testing, I was able to see that my tank uses most of its alkalinity from a few hours before lights out until a few hours after lights out. There is zero consumption from about midnight to 7am. I believe others have noticed that most of their consumption is towards the end of the photo period as well.

Awesome that is some good info that I was looking for!! Thank you!

 

[Reefltx]

Now that alkalinity monitors are available we are starting to get insight into daily demand. After a few weeks of hourly testing, I was able to see that my tank uses most of its alkalinity from a few hours before lights out until a few hours after lights out. There is zero consumption from about midnight to 7am. I believe others have noticed that most of their consumption is towards the end of the photo period as well.

Same here, my lowest alk is around 9-12pm, highest being in the morning before lights are on and a few hrs after. Therefore, I do my alk test at night.

 

[BluTang85]

Same here, my lowest alk is around 9-12pm, highest being in the morning before lights are on and a few hrs after. Therefore, I do my alk test at night.

What test kits do u use

 

[SPS Reefer]

Same here, my lowest alk is around 9-12pm, highest being in the morning before lights are on and a few hrs after. Therefore, I do my alk test at night.

So if someone was doing a blackout on their tank to cutback on any algae do you think they should trim their doser or CaRx down??

 

[Reefltx]

What test kits do u use

Mainly Hanna, salifert as backup.

Btw, I don’t have a alk monitor, I just tested my alk every 4hrs as experiment one weekend.

 

[BluTang85]

Mainly Hanna, salifert as backup.

I use primary Red Sea and salifert
How many tests do u get with the Hanna

 

[Reefltx]

I use primary Red Sea and salifert
How many tests do u get with the Hanna

25, I don’t really count. I buy 6 pack reagents at a time.

 

[Reefltx]

So if someone was doing a blackout on their tank to cutback on any algae do you think they should trim their doser or CaRx down??

Interesting question. I’ve never had to do a black out. But knowing what I know now, I’ll likely test before turning dosers back on.

 

[mike werner]

I use primary Red Sea and salifert
How many tests do u get with the Hanna

30

 

[BluTang85]

25, I don’t really count. I buy 6 pack reagents at a time.

Hanna more accurate?

 

[Big E]

I believe most of the growth is at night based on personal observations. Alk consumption levels are just telling when alk is taken up, not when the coral is growing.

I've noticed many times when my lights first come on I see coraline that has been kllled at the base of coral at the coraline interface. You can actually see some of the corals nematocysts and slime still there.

I examine my corals every morning the lights come on and this is when I see new sprouts show up as well. I'm not saying that it's only at night but by my own visual experiences they definitely grow during lights out.

 

[Big E]

Woops, sorry I focused on growth, not what you were asking about.

I don't think it's necessary to focus on such minutia as alk levels to the 10th or 1ooth degree over a 24 hour period, but if you think it's important than go for it.

 

[LobsterOfJustice]

So if someone was doing a blackout on their tank to cutback on any algae do you think they should trim their doser or CaRx down??

I do 3-day blackouts a few times a year, although I haven’t done one since I got the alk monitor. Usually I notice alk spike on the third day. It’s easy to adjust a dosing pump so I will skip a few doses on the third day to compensate, but for a CaRx I would likely leave it alone and just keep an eye on it.

 

[Jdavison911]

I have a Kh Guardian that test every 4 hours around the clock and does maintenance dosing to maintain my Kh at 8.5. What I have seen is most of my Kh maintenance dosing is done after the lights go out up til 2-4am. I have since switched my main dosing pumps to dose during those times to help stabilize. My Kh now runs 8.5 to 8.8 during a 24 hour period with 80% of my dosing happening throughout the night. Now with that being said Im not saying this is when my corals are using up the Kh because I do run a refuge full of life during the night to help with stabilizing my Ph so things maybe getting used up there as well. I also dose calcium around the clock not just during the night and maintain 420 any given day.