Bolus dosing

[Carni_Vora]

AI ?

Exactly. Not my mother language. I'd need to put up the kids for adoption if I'd write this on my own.

 

[reef_ranch]

I thought this was an interesting read: https://sci-hub.scrongyao.com/10.1016/j.ecss.2018.04.041

The study was done in a lagoon at Heron Island in the GBR. All measurements were taken at low tide (the lagoon is isolated from the ocean then) and the study found:

"Our automated time series revealed high temporal variability in alkalinity, pHT, and pCO2 during the observations (Figure 2), demonstrating the importance of continuous observations to characterize the dynamics of carbonate chemistry in coral reefs. Overall, the 3 measured parameters followed expected diel cycles with pCO2 and alkalinity dropping and pH increasing during the day as a result of calcification and photosynthesis (McMahon et al.,2013; Santos et al., 2011; Silverman et al., 2012). The overall observed range in alkalinity (2204.2 to 2418.7), pHT (7.85 to 8.43) and pCO2 (170 to 657) were comparable to previous studies in Heron Island (Albright et al., 2015; McMahon et al., 2013) and nearby coral reef lagoons (Shaw et al., 2012; Silverman et al., 2012) using lower frequency observations."

The alk measurements are in µmol kg-1 using Gran titration which is Greek to me. Randy, can you convert this to dkh or meq/l so we can understand what sort of swing this represents?

 

[Carni_Vora]

The study was done in a lagoon at Heron Island in the GBR. All measurements were taken at low tide (the lagoon is isolated from the ocean then) and the study found:

"Our automated time series revealed high temporal variability in alkalinity, pHT, and pCO2 during the observations (Figure 2), demonstrating the importance of continuous observations to characterize the dynamics of carbonate chemistry in coral reefs. Overall, the 3 measured parameters followed expected diel cycles with pCO2 and alkalinity dropping and pH increasing during the day as a result of calcification and photosynthesis (McMahon et al.,2013; Santos et al., 2011; Silverman et al., 2012). The overall observed range in alkalinity (2204.2 to 2418.7), pHT (7.85 to 8.43) and pCO2 (170 to 657) were comparable to previous studies in Heron Island (Albright et al., 2015; McMahon et al., 2013) and nearby coral reef lagoons (Shaw et al., 2012; Silverman et al., 2012) using lower frequency observations."

The alk measurements are in µmol kg-1 using Gran titration which is Greek to me. Randy, can you convert this to dkh or meq/l so we can understand what sort of swing this represents?

12.35 to 13.56 dkh

 

[Reefahholic]

The overall observed range in alkalinity (2204.2 to 2418.7)

I think the conversion to dKH is 1000 µmol/l (1 mmol/l) = 2.8 dKH. Multiply this with the sg of seawater at 35 psu - 1.0264.

Observed range from above was 2204 to 2418.

2.204 * 2.8 * 1.0264 = 6.334

2.418 * 2.8 * 1.0264 = 6.949

@Randy Holmes-Farley can you check that?

12.35 to 13.56 dkh

 

[MichaelM]

Concerning Bolus dosing with regular bicarb: I did test this morning.
Right before the Bolus I measured 6.7dkh @ PH 8.0. 20mins later it was 7.5dkh @ PH 8.1.
I dosed 10ml of 80g/l plain sodium bicarbonate solution into my 35l nano. This equates to a 0.8dkh increase in alkalinity which is exactly what my tests reflect. The tank is skimmerless btw.

I am using the bolus method for 1 1/2 weeks now. PH level seems a bit higher overall (8-8.4 instead 7.8-8.2) and I see an increase in coralline algae (I almost have none of these growing in my tank). Growth of Montipora seems to be faster, my Acropora millepora is still not growing (corals in this tank are generally slow growing).

 

[Welsh Reefer.]

Concerning Bolus dosing with regular bicarb: I did test this morning.
Right before the Bolus I measured 6.7dkh @ PH 8.0. 20mins later it was 7.5dkh @ PH 8.1.
I dosed 10ml of 80g/l plain sodium bicarbonate solution into my 35l nano. This equates to a 0.8dkh increase in alkalinity which is exactly what my tests reflect. The tank is skimmerless btw.

I am using the bolus method for 1 1/2 weeks now. PH level seems a bit higher overall (8-8.4 instead 7.8-8.2) and I see an increase in coralline algae (I almost have none of these growing in my tank). Growth of Montipora seems to be faster, my Acropora millepora is still not growing (corals in this tank are generally slow growing).

Skimmer seems to be a key factor mentioned many times, interesting results all the same and makes me look forward to trying it later in the week to see if there is a difference when running a skimmer!

Good to see despite this you are seeing good results, did you test alk any more throughout the photo period, assume you don't have an auto tester?

 

[Kennya]

Concerning Bolus dosing with regular bicarb: I did test this morning.
Right before the Bolus I measured 6.7dkh @ PH 8.0. 20mins later it was 7.5dkh @ PH 8.1.
I dosed 10ml of 80g/l plain sodium bicarbonate solution into my 35l nano. This equates to a 0.8dkh increase in alkalinity which is exactly what my tests reflect. The tank is skimmerless btw.

I am using the bolus method for 1 1/2 weeks now. PH level seems a bit higher overall (8-8.4 instead 7.8-8.2) and I see an increase in coralline algae (I almost have none of these growing in my tank). Growth of Montipora seems to be faster, my Acropora millepora is still not growing (corals in this tank are generally slow growing).

Would be interested if you have dKH and pH measurements at the same times when using FM's carbonate mix to compare with the pure bicarbonate.

 

[Randy Holmes-Farley]

I don't claim I am a reef chemist or whatever and I mentioned specifically places with river input. Here are some points that influence alkalinity in the water, if you have scientific proof against all of them, go ahead.



1. Biological Activity:
• Photosynthesis: During photosynthesis, phytoplankton consume carbon dioxide, which can increase alkalinity.
• Respiration and Decomposition: The respiration of organisms and the decomposition of organic matter produce carbon dioxide, which can decrease alkalinity.
2. Freshwater Input:
• River Discharge: Rivers bring freshwater into the ocean, which typically has lower alkalinity compared to seawater. This influx can dilute ocean water, reducing its alkalinity.
• Precipitation: Rainwater, which has low alkalinity, can decrease surface water alkalinity, especially during heavy rainfall events.
3. Ocean Mixing and Currents:
• Upwelling: Upwelling brings deep, nutrient-rich, and often more alkaline waters to the surface, which can increase surface water alkalinity.
• Downwelling: Downwelling can move surface waters, along with their characteristics, deeper into the ocean.
4. Seasonal Variations:
• Seasonal changes in temperature, biological productivity, and mixing processes can cause periodic fluctuations in surface water alkalinity.

Human Influences:

1. Pollution:
• Agricultural Runoff: Nutrients from fertilizers can lead to algal blooms. When these blooms decompose, they can alter the chemical composition of the water, affecting alkalinity.
• Industrial Discharges: Wastewater from industrial processes can introduce chemicals that alter the alkalinity of coastal waters.
2. Climate Change:
• Ocean Acidification: Increased atmospheric CO2 levels lead to higher CO2 concentrations in seawater, which can decrease alkalinity by forming carbonic acid and altering carbonate chemistry.
• Changes in Precipitation Patterns: Climate change can affect the amount and distribution of rainfall, influencing freshwater input into the ocean.
3. Land Use Changes:
• Deforestation and Urbanization: These activities can increase the amount of sediment and nutrients entering the ocean, affecting coastal water chemistry and alkalinity.

Implications of Alkalinity Variability:

• Carbonate Chemistry: Fluctuations in alkalinity affect the carbonate system, influencing the saturation states of calcium carbonate minerals, which are crucial for the health of calcifying organisms such as corals and shellfish.
• Buffering Capacity: Changes in alkalinity alter the ocean’s ability to buffer against pH changes, impacting overall marine ecosystem resilience to ocean acidification.
• Ecosystem Health: Variations in alkalinity can affect the distribution and health of marine organisms, particularly those sensitive to changes in water chemistry.

Surface ocean water alkalinity is influenced by a range of natural processes and human activities that can cause significant variability. These fluctuations have important implications for marine chemistry, ecosystem health, and the ocean’s capacity to buffer against pH changes.

Noting uses and sources of alk does not imply it is unstable. There are many sources and sinks for O2 in air, but the O2 level is stable.

You also have many misunderstandings of what impacts alk.

Photosynthesis has zero impact on alkalinity. Adding or removing CO2 cannot impact alkalinity.

Algal blooms and deaths do not significantly impact alk.

 

[Randy Holmes-Farley]

12.35 to 13.56 dkh

That is not correct.

 

[Randy Holmes-Farley]

I think the conversion to dKH is 1000 µmol/l (1 mmol/l) = 2.8 dKH. Multiply this with the sg of seawater at 35 psu - 1.0264.

Observed range from above was 2204 to 2418.

2.204 * 2.8 * 1.0264 = 6.334

2.418 * 2.8 * 1.0264 = 6.949

@Randy Holmes-Farley can you check that?

I would not put in the salinity correction, but that change is small.

2,204 uM = 2.2 mM = 6.2 dKH

That change is small and is in a lagoon, not the open water.

 

[Randy Holmes-Farley]

I am using the bolus method for 1 1/2 weeks now. PH level seems a bit higher overall (8-8.4 instead 7.8-8.2) and I see an increase in coralline algae (I almost have none of these growing in my tank). Growth of Montipora seems to be faster, my Acropora millepora is still not growing (corals in this tank are generally slow growing).

Compared to what method used previously?

Did you note the pH right after dosing?

 

[Randy Holmes-Farley]

Skimmer seems to be a key factor mentioned many times, interesting results all the same and makes me look forward to trying it later in the week to see if there is a difference when running a skimmer!

Good to see despite this you are seeing good results, did you test alk any more throughout the photo period, assume you don't have an auto tester?

the higher the aeration, the faster will the pH drop from bicarbonate be converted into a pH rise. Likewise, the higher the aeration the faster a pH rise from carbonate or hydroxide will be reduced to just the alk effect in pH rise.

 

[Randy Holmes-Farley]

Unrelated to bolus dosing but relevant to this post from Randy - If the pH of the solution is between 9 and 11 (9.84), can one assume it is a mix of carbonate/bicarbonate?

I would assume it is at least not pure bicarbonate. At the pH 11 end it might be pure carbonate.

 

[Randy Holmes-Farley]

Exactly. Not my mother language. I'd need to put up the kids for adoption if I'd write this on my own.

You need a better AI. This one made lots of mistakes about what impacts alkalinity.

 

[Garf]

makes me look forward to trying it later in the week

Can I suggest you try it with just enough normal bicarb to increase Alk to your measured high. Adding 2 DKH bicarb will raise ALK by 2 DKH and may make your tank gods angry.

 

[Randy Holmes-Farley]

Can I suggest you try it with just enough normal bicarb to increase Alk to your measured high. Adding 2 DKH bicarb will raise ALK by 2 DKH and may make your tank gods angry.

The bigger the alk boost, of course, the bigger will be any pH rise after the tank blows off the excess CO2. A 6 to 8 dKH change to alk increases pH by about 0.12 pH units after full equilibration with the air.

OTOH, if the goal is higher pH during the day, using higher pH alk additives would have a larger effect before full aeration, and dosing carbonate or hydroxide through the photo period can give more stable alk and the same or higher pH.

 

[RandomReefer420]

Adding 2 DKH bicarb will raise ALK by 2 DKH and may make your tank gods angry.

If Welsh Reefer changes two variables ( bicarb/fauna carbonate and the quantity ) isn't that going to make it harder to draw any conclusions ?

 

[Welsh Reefer.]

The bigger the alk boost, of course, the bigger will be any pH rise after the tank blows off the excess CO2. A 6 to 8 dKH change to alk increases pH by about 0.12 pH units after full equilibration with the air.

OTOH, if the goal is higher pH during the day, using higher pH alk additives would have a larger effect before full aeration, and dosing carbonate or hydroxide through the photo period can give more stable alk and the same or higher pH.

So is this a change of position from the 'every reefer knows that dosing bicarbonate does not increase pH' statement you'd made previously?

 

[Welsh Reefer.]

If Welsh Reefer changes two variables ( bicarb/fauna carbonate and the quantity ) isn't that going to make it harder to draw any conclusions ?

I'll stick with 2dKH, what's the worst that can happen

 

[Garf]

So is this a change of position from the 'every reefer knows that dosing bicarbonate does not increase pH' statement you'd made previously?

Not when maintaining alkalinity, it's the increase in alkalinity that affects pH a little.