Chicken/egg problem for Alk/Ca/PH?

[arking_mark]

I had to stop my skimmer for 72hrs to treat a fish. I maintained the ~1dKH Kalk drip and found my pH slowly dropping while my dKH rose.

My current pH is has dropped to about 8.18 and may continue to drop and my alk has gone from 7.6 to 8.6 and may continue to rise.

As the skimmer and CO2 scrubber start back up today, I expect my pH to rise and alk to stop rising and potentially come down.

Red indicates when I stopped my skimmer and CO2 scrubber and blue indicate when I turned it on this morning.

So at least for my tank, a 4-month old tank, I needed to get pH up 1st to be able to dose enough Kalk to get a nice feedback loop to help keep pH stable at a level higher than what would be normally 7.9 in my tank do to higher CO2 house air.

It's easy to check the strength of the Kalkwasser with an EC meter to know when to add more Kalk.

It's harder to assess the CO2 scrubbing material as it doesn't color change well. In my case, the bottom portion turned pink, and then the pink disappeared over time. I'm pretty sure the bottom is exhausted...but not sure about the top portion. I'm thinking a dual-stage CO2 scrubber may be best to get the most out the CO2 scrubber media. It's a trick I use (and many others) for DI in my RODI system.

 

[schuby]

@arking_mark , it is probably just ignorance on my part, but I don't understand your obsession with high PH. From the one pic, your rock is almost all still white and you appear to have almost no creatures that grow, creating calcium-based structures (such as coraline algae, SPS, LPS). How can you have transferred from a 7+ year-old tank when your rock seems very new. What, if anything, was transferred?

If this is simply an experiment in artificially creating high PH in an inddor tank full of saltwater, then you are having amazing success. I greatly admire your attention to detail and your work ethic. I'm just not understanding your motive.

 

[arking_mark]

@arking_mark , it is probably just ignorance on my part, but I don't understand your obsession with high PH. From the one pic, your rock is almost all still white and you appear to have almost no creatures that grow, creating calcium-based structures (such as coraline algae, SPS, LPS). How can you have transferred from a 7+ year-old tank when your rock seems very new. What, if anything, was transferred?

If this is simply an experiment in artificially creating high PH in an inddor tank full of saltwater, then you are having amazing success. I greatly admire your attention to detail and your work ethic. I'm just not understanding your motive.

Great question. How I got here...

1. The goal was for my next tank (this new one) to be ultra-low maintenance (ULM)
2. ULM to me means simplifying and minimizing maintenance
3. Getting the tank stable is key to success and I was having issues with Alk stability and issues with newer coral frags added to the tank
4. Coral growth is enhanced by more natural pH (8.3) and elevated Ca/Alk per some studies I've looked at
5. So targeting a stable environment with NSW or slightly higher pH/Ca/Alk was something I started to target
6. Kalkwasser dosing seemed like a great start. However, my Alk demand was very haphazard and Kalkwasser automated controlled dosing wasn't working.
7. This lead to me looking into "unlocking" Alk consumption so I could consistently dose Kalkwasser and get its pH/Ca/Alk benefits.
8. Getting pH to 8.3ish turned out to be the solution. The NSW pH allowed increased Alk consumption.
9. The last step for me was to automate everything...and minimize maintenance. Which is where I am today.

 

[arking_mark]

@Randy Holmes-Farley

So I might have found the CaCO3 abiotic precipitation.

This rock is probably a river rock. I saved it from my old 180 reef tank that I shut down 12 years ago.

It got a week long bleach bath prior to setting up this tank.

I think the white all over it was there from the start. It was probably old coralline algae or something.

I'm thinking that CaCO3 tends to precipitate and build up on CaCO3. So this rock may be building up more and more CaCO3.

Thoughts?

 

[arking_mark]

@Randy Holmes-Farley

So I might have found the CaCO3 abiotic precipitation.

This rock is probably a river rock. I saved it from my old 180 reef tank that I shut down 12 years ago.

It got a week long bleach bath prior to setting up this tank.

I think the white all over it was there from the start. It was probably old coralline algae or something.

I'm thinking that CaCO3 tends to precipitate and build up on CaCO3. So this rock may be building up more and more CaCO3.

Thoughts?

Found a picture of the rock when I 1st got the tank wet...

 

[arking_mark]

For those still following along...to treat a fish, I had to shut down the skimmer for another 48hrs and here is what I observed.

• With the skimmer off, I had a very rapid pH decline and a large Alk increase which caused me to stop dosing Kalk and a further decrease of pH
• With the skimmer back on, I had a rapid increase in pH and a decrease in Alk which allowed me to turn the Kalk dosing back on
• Steady-state with higher pH seems to allow me to dose 1dKH of Kalk per day

@Randy Holmes-Farley A couple of questions

1. There seems to be a direct relationship in my tank for pH and Alk (which makes sense as both are related). Do you have an article or could you provide the chemistry behind this relationship? Is there a simple rule of thumb for this relationship?
2. Clearly, the higher pH allows my tank to consume more Alk. As I only have a few corals in the tank, I'm guessing most of this consumption is abiotic. I thought I read somewhere that calcium carbonate will precipitate well on itself. As I have a rock with a ton of old calcium carbonate on it, could that account for this abiotic uptake? Or is it happening elsewhere and I'm just not aware (is this going to bite me in the butt sometime in the future)?