Elevated + Stable pH solution?

[Munns!]

Co2 Scrubbers are often a solution to low pH problems; however, they are hard to control which often leads to elevated but not stable pH levels.


Controllability:
One could use a solenoid or ball valve on the air intake of a recirculating Co2 scrubber and cause the air to be taken in from the sump instead of the already scrubbed air from the skimmer cup; this would serve as a way to pinpoint one’s pH and keep it stable. However, this solution often requires a great deal of DIY expertise, and it can be difficult to initially set up.

Additionally, one could simply set their Protein skimmer to shut off once their desired pH level is reached and the turn back on when it it begins to drop. However, this also greatly hinders one’s protein skimmer’s effectiveness at removing excess organics.

I was thinking that one could buy a stand alone protein skimmer pump, using tubing for the air intake, and connect it to one’s Co2 scrubber. Then the pump could be connected to one’s aquarium controller. Now, one could easily raise and stabilize their pH without jeopardizing their protein skimmer’s performance or going through the hassle of trying to use a solenoid or ball valve on the air intake.

How effective would this method be? Does it work? Has anyone tried something similar to this?

All experiences and opinions are welcome and appreciated!

 

[Munns!]

bump

 

[DJF]

Another option… an air pump plumbed to pull air from outside (thru carbon) independent of the skimmer controlled by a smart plug.

 

[Randy Holmes-Farley]

I think one question is on the benefit of a stable pH. For example, is a steady 8.3 better or worse than a range from 8.3 to 8.5, or some such comparison.

That said, some folks have aimed for pH control in other ways, such as controlling what alk additives are used based on pH. I think Miami did this, but didn’t notice any clear benefit. Was that true Miami?

@Miami Reef

 

[Subsea]

I think one question is on the benefit of a stable pH. For example, is a steady 8.3 better or worse than a range from 8.3 to 8.5, or some such comparison.

That said, some folks have aimed for pH control in other ways, such as controlling what alk additives are used based on pH. I think Miami did this, but didn’t notice any clear benefit. Was that true Miami?

@Miami Reef

Because I never went with alkalinity demanding SPS, I emulate Nature. Normal pH fluctuation on a healthy IndoPacific reef is 8.2 to 7.8. In my experience, low oxygen during lights out is a much more serious issue in our captive reefs. In my case, I also get some passive trace mineral and some alkalinity buffering in aragonite substrate.

 

[Miami Reef]

I think one question is on the benefit of a stable pH. For example, is a steady 8.3 better or worse than a range from 8.3 to 8.5, or some such comparison.

That said, some folks have aimed for pH control in other ways, such as controlling what alk additives are used based on pH. I think Miami did this, but didn’t notice any clear benefit. Was that true Miami?

@Miami Reef

My pH is pretty stable, but I don’t do anything special to maintain it.

I use sodium hydroxide with a BRS 1.1mL pump that evenly doses every hour around the clock.

I have a CO2 scrubber that I very recently added. I now use it sparingly to give an extra oomph when needed.

I’m having really good growth. I try to keep my alk around 9dKH.

My pH range from 8.3 to 8.4

 

[Randy Holmes-Farley]

My pH is pretty stable, but I don’t do anything special to maintain it.

I use sodium hydroxide with a BRS 1.1mL pump that evenly doses every hour around the clock.

I have a CO2 scrubber that I very recently added. I now use it sparingly to give an extra oomph when needed.

I’m having really good growth. I try to keep my alk around 9dKH.

My pH range from 8.3 to 8.4

Sorry, perhaps i confused you with someone else who tried to actively control pH. :)

 

[Miami Reef]

Sorry, perhaps i confused you with someone else who tried to actively control pH. :)

Hi. I just wanted to clarify that you didn’t confuse me for someone else. I was the one who wondered if it was possible to do it without alkalinity getting too high.


I found a method that I have been testing since yesterday. It involves a 24/7 CO2 scrubber to prevent the alkalinity from getting too high. I selected a slight surplus of sodium hydroxide spread around the clock every hour.


If the probe's pH is above 8.45, the doser will not add any additives.


This method requires me to calibrate the probe at least once per month to ensure optimal accuracy.


My pH graph is here. The stable part is when I started the method. I never cared about alkalinity as long as it is between 8 and 12 dKH; I care more about pH.

 

[Randy Holmes-Farley]

Hi. I just wanted to clarify that you didn’t confuse me for someone else. I was the one who wondered if it was possible to do it without alkalinity getting too high.


I found a method that I have been testing since yesterday. It involves a 24/7 CO2 scrubber to prevent the alkalinity from getting too high. I selected a slight surplus of sodium hydroxide spread around the clock every hour.


If the probe's pH is above 8.45, the doser will not add any additives.


This method requires me to calibrate the probe at least once per month to ensure optimal accuracy.


My pH graph is here. The stable part is when I started the method. I never cared about alkalinity as long as it is between 8 and 12 dKH; I care more about pH.

Thanks.

What if the pH is above 8.45 but alk is dropping?

 

[Miami Reef]

Thanks.

What if the pH is above 8.45 but alk is dropping?

It depends on how low the alk gets. If it stays above 7.5dKH, I likely won’t do anything about it as long as the pH is high. I believe most of the alk will naturally be dosed at night.


It’ll be interesting to track the alkalinity with this method. My alk is currently 10dKH.



I’ve been wondering lately about high (boric/borate?) alk salt mixes (like Seachem’s) that show elevated alk but don’t actually contain much bicarbonate/carbonate.



Is there a test to determine if a salt mix has elevated borate? If it does, would it be possible to drop all the alk with muriatic acid and then replenish it with sodium bicarbonate (outside the tank)?



Of course, I don’t have this issue. It’s just a curious thought I had. All my reef’s water came from the ocean.

 

[Randy Holmes-Farley]

It depends on how low the alk gets. If it stays above 7.5dKH, I likely won’t do anything about it as long as the pH is high. I believe most of the alk will naturally be dosed at night.


It’ll be interesting to track the alkalinity with this method. My alk is currently 10dKH.



I’ve been wondering lately about high (boric/borate?) alk salt mixes (like Seachem’s) that show elevated alk but don’t actually contain much bicarbonate/carbonate.



Is there a test to determine if a salt mix has elevated borate? If it does, would it be possible to drop all the alk with muriatic acid and then replenish it with sodium bicarbonate (outside the tank)?



Of course, I don’t have this issue. It’s just a curious thought I had. All my reef’s water came from the ocean.

There are (or were) borate test kits, but they aren't all that great. ICP is fine. Seachem lowered the borate a few years back, and it may not be the problem it used to be.

 

[Miami Reef]

What if the pH is above 8.45 but alk is dropping?

I have some new ideas if the alk is dropping too low from elevated pH limitations:

1) Meter the CO2 scrubber (my least preferred option based on my scrubber setup.)

2) More aeration through the top tank to allow more alk additives.

3) (My favorite idea) Mix 1:1 sodium carbonate to hydroxide for my alk additive. If the pH still limits the amount of alk added, use only sodium carbonate.

The premise is to find a way to slightly reduce pH so more alk additives can enter the tank.

 

[Randy Holmes-Farley]

I have some new ideas if the alk is dropping too low from elevated pH limitations:

1) Meter the CO2 scrubber (my least preferred option based on my scrubber setup.)

2) More aeration through the top tank to allow more alk additives.

3) (My favorite idea) Mix 1:1 sodium carbonate to hydroxide for my alk additive. If the pH still limits the amount of alk added, use only sodium carbonate.

The premise is to find a way to slightly reduce pH so more alk additives can enter the tank.

A really automated system could:

1. Switch between scrubbed and room air (or outdoor and indoor air) based on a desired pH range
2. Switch between carbonate and hydroxide based on pH, and only dosed based on alk needs.

 

[Miami Reef]

A really automated system could:

1. Switch between scrubbed and room air (or outdoor and indoor air) based on a desired pH range
2. Switch between carbonate and hydroxide based on pH, and only dosed based on alk needs.

The first option makes sense.

The second one would be confusing because I add a gallon of calcium and balling when I finish a gallon of the alk (they are added simultaneously within the hour.)

 

[Randy Holmes-Farley]

The first option makes sense.

The second one would be confusing because I add a gallon of calcium and balling when I finish a gallon of the alk (they are added simultaneously within the hour.)

Not confusing if you turn the tank over to an AI. Lol

 

[Miami Reef]

@Randy Holmes-Farley

I need your opinion.

The pH was getting too high with the CO2 scrubber, so I haven’t needed it at all.

At first, the sodium hydroxide maintained my pH and alkalinity perfectly.

However, I’m having an issue where the pH is being maintained at a high level (8.4) but my alk is in the 7’s.

I tried increasing the pH threshold to allow more alkalinity to be added, but I’m having the same issue as the past where I’m adding a lot of alk, and only the pH is being maintained, while the alk is dropping.

I don’t see significant precipitation, but I did have a ton of coralline growth.

If corals and coralline consume alkalinity, does the pH naturally drop a little?

The pH is being maintained perfectly, but the alkalinity is too low. What gives?

 

[Miami Reef]

I manually raised the alk with sodium bicarbonate and will try to maintain 8.25pH with sodium carbonate.

I’m interested in seeing what alk level the tank will stabilize on.

 

[Randy Holmes-Farley]

It’s a complicated question. Calcium carbonate deposition lowers pH and alk, being the exact opposite of adding carbonate.

If you replace carbonate with carbonate, it’s a net neutral process. If you replace carbonate with bicarbonate, it’s a net pH lowering process. If you replace carbonate with hydroxide, it’s a net pH raising process.

My guess is that the high pH is causing more organism consumption and more abiotic precipitation, even if you don’t see it.

Switching to bicarbonate will almost certainly lower pH and alk demand. That is not necessarily a good or bad thing, just a choice to make. :)

 

[Miami Reef]

No no. I was trying to say that I was thinking of switching to sodium carbonate from sodium hydroxide.

I believe there is a lot of abiotic precipitation that is not visible to my eyes. I added a small bowl of sand last week, and when I went to change it last night (too fine for clams) I noticed a lot of precipitation in it.

I’m sure it’s also happening elsewhere.

I think the issue was maintaining a really high pH (8.4-8.5)

 

[Randy Holmes-Farley]

I believe there is a lot of abiotic precipitation that is not visible to my eyes. I added a small bowl of sand last week, and when I went to change it last night (too fine for clams) I noticed a lot of precipitation in it.

I’m sure it’s also happening elsewhere.

Yes, that makes sense. :)