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Chasing Stable Alk - APEX Alk Test Every Hour For Over 24 Hours


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Thoughts:

- Alk stability is known to be very important in reef keeping.

- We run the CR at the same flow and PH 24x7, but the alk demand is not steady during that same period.

- Can the solenoid be shut off for certain periods and / or the PH be lowered certain periods to balance it out?

 

The ultimate stable alk?

Below are the results of testing every hour for 24 hours.  This also confirms many months of testing every six hours.   The higher resolution is nice though and gives better data for conclusions or actions.

 

- Alk peaks at 11:10 AM both days.

- Alk lows are at about 6:00 PM both days

 

Twice the CR solenoid was shut off because alk was getting too high, between 11 am and 1 pm.

My ultimate goal is to flatten out the peaks and valleys, get alk as stable as possible.

Going forward, shutting off the solenoid around 2-3 am may make sense along with running a slightly lower reactor PH when during the rest of the day.  

 

 

image.png

 

 

 

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1 hour ago, Aquanius said:

Yeah this is great.  I am just trying to get my PH and ALK back to reasonable levels before I throw my calc reactor back on.  I have the trident testing and I have a huge drop in ALK at around 9pm every night, about 30min after lights out.

Isn't that crazy how coral sucks down the alk right after lights out?  I felt surprised by that data, but never tested enough to even wonder!

 

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So cool. This is incredible that the hobby is getting to the point we can detect and think about adjusting these daily fluctuations in alkalinity. 

Since pH isnt stable on natural reefs, I was motivated to look at the research literature to ask, how does your variation in alkalinity compare to natural coral reefs? 

Picture3.jpg.5c2ee2bac1f768bf07769eb3320aefb1.jpg

This study (reference here) also found alkalinity dropped during the daytime by about 7%. (Its shown as "TA", for total alkalinity) I guess the daytime drop in alkalinity is driven by photosynthesis? 

Interesting that this pattern is opposite the variation in corals' demand for alkalinity. I suspect the increased demand after lights out has to do with the falling pH, which will convert carbonate into bicarbonate. Corals take up bicarbonate, so it would make sense that uptake would increase at night when the pH falls and the bicarbonate rises. I think thats how it works, anyway!

 

 

Edited by EMeyer
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1 hour ago, EMeyer said:

So cool. This is incredible that the hobby is getting to the point we can detect and think about adjusting these daily fluctuations in alkalinity. 

Since pH isnt stable on natural reefs, I was motivated to look at the research literature to ask, how does your variation in alkalinity compare to natural coral reefs? 

Picture3.jpg.5c2ee2bac1f768bf07769eb3320aefb1.jpg

This study (reference here) also found alkalinity dropped during the daytime by about 7%. (Its shown as "TA", for total alkalinity) I guess the daytime drop in alkalinity is driven by photosynthesis? 

Interesting that this pattern is opposite the variation in corals' demand for alkalinity. I suspect the increased demand after lights out has to do with the falling pH, which will convert carbonate into bicarbonate. Corals take up bicarbonate, so it would make sense that uptake would increase at night when the pH falls and the bicarbonate rises. I think thats how it works, anyway!

 

 

 

Oh, this is great, very interested!  Let me add PH to that chart in case it helps the discussion!

 

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Just now, Aquanius said:

@TheClark Any tips on keeping the pH up?  I am looking at getting a CO2 scrubber because I keep having it drop to 7.6-7.7 on average.

That's a tough topic for me.  I too struggled.  Ran a scrubber for a while, but it went through media so fast.  Finally I moved the skimmer intakes to the outside window.  That helped allot, and I just tend to keep windows open all year long now.  Is your alk ok?

Did you check out RHF article on this?

http://www.reefkeeping.com/issues/2004-09/rhf/#:~:text=In my opinion%2C the pH,end of this pH range.

 

 

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Yeah I was going to use the scrubber for now because I can't run the line outside with all of the fires going on.  I might just add a carbon block to an outside line.

I wonder if the fires are making the insides of the house have a greater CO2 load with everything being shut + any additional CO2 in the air from the burn.

Either way I need to get the PH up, it's been down for a while.

 

Yeah Alk is between 8.0 and 8.3 on average now.  Didn't want to hookup the calcium reactor until I get the PH sorted.

Edited by Aquanius
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1 hour ago, TheClark said:

Added PH!  Thanks @EMeyer

It's incredible to think in the vast ocean that alk drops 7% in the day time.  

 

I should clarify that the study I cited was from a lagoon at Heron Island on the GBR, where there is limited exchange with the open ocean during part of the day. So these effects are probably different here than in the open ocean. Still, its a typical coral habitat so I figured it was a relevant number to add to the discussion. 

I'm often struck by the fact that on real reefs, most of the parameters we try to keep stable in our aquariums, are not stable at all. Temperature, light, pO2, pCO2, pH, alkalinity. The only cycle we ever try to mimic is light. The others, we (the reefkeeping community) try to maintain at stable levels, in some cases levels that aren't near the average. 

But I hadnt really dug into the alkalinity part until your post, I'm still doing manual dKH titrations so I don't see these patterns :)

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6 hours ago, Aquanius said:

Yeah I was going to use the scrubber for now because I can't run the line outside with all of the fires going on.  I might just add a carbon block to an outside line.

I wonder if the fires are making the insides of the house have a greater CO2 load with everything being shut + any additional CO2 in the air from the burn.

Either way I need to get the PH up, it's been down for a while.

 

Yeah Alk is between 8.0 and 8.3 on average now.  Didn't want to hookup the calcium reactor until I get the PH sorted.

CO2 monitors can be had pretty reasonably now, thanks to the indoor growing industry I suppose!

 

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5 hours ago, EMeyer said:

I should clarify that the study I cited was from a lagoon at Heron Island on the GBR, where there is limited exchange with the open ocean during part of the day. So these effects are probably different here than in the open ocean. Still, its a typical coral habitat so I figured it was a relevant number to add to the discussion. 

I'm often struck by the fact that on real reefs, most of the parameters we try to keep stable in our aquariums, are not stable at all. Temperature, light, pO2, pCO2, pH, alkalinity. The only cycle we ever try to mimic is light. The others, we (the reefkeeping community) try to maintain at stable levels, in some cases levels that aren't near the average. 

Excellent point, but at least we have actual data, thanks for that.  I wouldn't be surprised if new patterns emerge out of the Apex data, too. Each species is going to be optimized for their particular environment and we're trying to force them all together for our convenience. There's going to be metabolic variations between species and the overall tank metabolism depending on the mix of corals. Obviously mixed vs sps  dominant is a huge difference. I guess the key is recognizing the rhythms of your particular tank. 

What a f'n interesting hobby. 
 

Does anyone know what schools are the big coral research facilities? Might be able to get a PowerPoint on the subject. On the flip side, all this collected Neptune data should get crunched a la Seti@home. 

Edited by half-astronaut
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On 9/14/2020 at 3:54 PM, TheClark said:

That's a tough topic for me.  I too struggled.  Ran a scrubber for a while, but it went through media so fast.  Finally I moved the skimmer intakes to the outside window.  That helped allot, and I just tend to keep windows open all year long now.  Is your alk ok?

Did you check out RHF article on this?

http://www.reefkeeping.com/issues/2004-09/rhf/#:~:text=In my opinion%2C the pH,end of this pH range.

 

 

Did you try recirculating the co2 scrubber into the top of the skimmer lid? Making sure it is on the outside of where the foam comes up.

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