Low pH with kalkwasser

[Key Largo]

I'm kinda hoping that there is some chemistry interaction that I'm not understanding that may be the problem. 6 YO 135 gallon total volume with sump. Skimmer connected to outside air via hose. Kalk dosed separate from ATO. Also dosing Acropower and BRS general adjustment magnesium. Daily additions of DIY NoPox and occasionally LaC (Phosphate RX) to keep phosphate in check. I have 10 Fish, including an adult sized Hippo and Flagfin Angel. Mixed reef with Leathers and Montis and Acros. Great Monti, Chalice growth, moderate/slow Acro growth. I feed DIY frozen melange equivalent to 3-4 cubes a day. Salinity 1.026 (pinpoint salinity monitor for conductivity) 25 gal per month water change with reef crystals.
The situation is thus, been dosing Kalk since tank inception. For last three years pH was 8.2-8.4 (pinpoint, calibrated every month) measured in sump. I only test Alk and Po4 (average .12) regularly, Mg, Nitrate (average 15), Ca occasionally. pH stared dropping to where i can no longer keep it above 8.0 and it fluctuates down to 7.6-7.7 at night. So of course I tested all parameters. I found that my Ca was over 500 and Mg over 1500. I had my Kalk dosing 2.2 ml per minute to keep up with Alk demand (which is always higher than CA demand. Alternately I would add some liquid baking soda to make up for Alk deficiency. I was keeping my Alk at 8.0. So I was pumping in a large amount of Kalk and my pH was still decreasing. Since taking new readings showing elevated levels of CA and Mg I cut back my Kalk additions and Mg dosing until those levels come back in line. To compensate for Alk demand in the meantime I have been adding liquid soda ash instead of liquid baking soda, as per Mr. Farley articles saying that is the preffered additive of the two for tanks with lower pH. Im also using it to slowly bring my alk up to 9.0. The condition of my inhabitants is ok, I am usually of the school that plenty of tanks run at that pH, so don't chase numbers. But in my case the numbers WERE higher ansd stable for a long time and then started dropping. I thought Kalk additions would always keep my pH at elevated levels. Thats why i'm wondering if there is not some chemistry imbalance point I am missing.

 

[Randy Holmes-Farley]

When did you last calibrate the pH meter?

There is no mechanism for limewater (kalkwasser) or soda ash dosing to reduce pH in any way.

NOPOX lowers pH, as does elevated indoor CO2. Closed up home due to weather will lower pH.

Limewater will slowly raise calcium when dosed to maintian alk. The magneisum is either from dosign too much, high mag salt muix, or test error.

 

[Key Largo]

Thank you for the reply. As stated I calibrate monthly. Also use outdoor air to skimmer. have CO2 monitor near tank (Basement). usually 600+. That is why I also cut down on water surface turbulence as I thought I might be working at cross purposes and adding CO2. I also dont/didnt know if elevateed Calcium and magnesium had any effect on pH. I have cut down my dosing of both, less kalk less Mg. Would NoPox additions have that much of an effect? This problen is 6 months old and have been dosing NoPox for years. My question for concern is what else beside high CO2 in the air would stop my pH from being raised via Kalk?

 

[Key Largo]

Another tangent question, besides outside air to my skimmer, does anyone have an idea for injecting more outside air either directly into tank or sump?

 

[Dburr1014]

Another tangent question, besides outside air to my skimmer, does anyone have an idea for injecting more outside air either directly into tank or sump?

Have you tried opening a window for a couple hours? See if the ph climbs.
How old is your probe? It does require replacement every so often.

 

[Key Largo]

Actually, the probe is brand new (1 month) because i dropped the last one trying to clean it before calibrating. Have tried opening windows, but that is a temporary fix. Security concerns with leaving them open all the time, and winter here in the NE precludes that. I'm thinking maybe a pond aerator located outside the house with lines into DT, on a timer. I guess i'm just having a hard time grasping that high home CO2 levels are enough to totally overcome additions of limewater. Then what would my pH be without Kalk? like 6, lol.

 

[Acros]

Did you notice the ph drop after cutting down surface agitation?

 

[Key Largo]

pH rose maybe slightly. but didnt get worse. didnt want to remove surface agitation altogether, so now the wavemake is on 50-50 setting and lower in the water column

 

[Randy Holmes-Farley]

Calcium and magnesium dosing or levels have no impact on pH.

The effect of NOPOX will depend on how much you use, but if you dose upstream of a pH probe you will see the immediate drop from the acetic acid in it. Then, over time, the organics are metabolized to CO2, which also lowers pH.

 

[Key Largo]

Ok, No correlation with high Ca or high Mg to pH drop. Metabolized organically converting to cO2 is interesting. I would think then that it would the case with all carbon dosing? So, enough cO2 in water will negate the pH raising properties of limewater to an extent? By combining with the carbonate in kalk? Is there an additive/ carbonate source that would mitigate that? Or offset.

 

[Randy Holmes-Farley]

Ok, No correlation with high Ca or high Mg to pH drop. Metabolized organically converting to cO2 is interesting. I would think then that it would the case with all carbon dosing? So, enough cO2 in water will negate the pH raising properties of limewater to an extent? By combining with the carbonate in kalk? Is there an additive/ carbonate source that would mitigate that? Or offset.

All carbon dosing tends to lower pH (though some schemes mix high pH alk additives into it).

Any source of CO2 (most often home air) can offset attempts to raise pH.

No additive can raise pH or offset CO2 without adding alkalinity, and hydroxide (as in kalkwasser or a very high pH two part) has the highst pH boost per unit of alk added.

 

[Dburr1014]

High CO2 in the home can drive down the ph even with the Kalk.
Can you share more about your system?
Do you have a sump under the tank?
The CO2 monitor you said is in the basement, is this where your system is also located?

For me personally, I am adding Kalk 100% with my ATO. I add 3 tablespoons every 3 days to the Kalk reactor just to stay north of 7.8 PH. The reactor is about 1.25 gallons. I can see in my PH graph that it steadily declines if I miss a day or even have company over it dips below 7.8
(grandkids have been sleeping over on weekends quite a bit lately)
My display is on the first floor and sump is in the basement. Skimmer is fed with a line outside.
CO2 can definitely have an impact.

 

[Key Largo]

High CO2 in the home can drive down the ph even with the Kalk.
Can you share more about your system?
Do you have a sump under the tank?
The CO2 monitor you said is in the basement, is this where your system is also located?

For me personally, I am adding Kalk 100% with my ATO. I add 3 tablespoons every 3 days to the Kalk reactor just to stay north of 7.8 PH. The reactor is about 1.25 gallons. I can see in my PH graph that it steadily declines if I miss a day or even have company over it dips below 7.8
(grandkids have been sleeping over on weekends quite a bit lately)
My display is on the first floor and sump is in the basement. Skimmer is fed with a line outside.
CO2 can definitely have an impact.

Seems like you have a similar circumstance to mine. yes I have a sump under DT, located in basement, along with monitor. I use a 5 gallon reservoir with saturated kalk (measured by conductivity) that I have on a continuous dose. I guess my original question arose from the idea that CO2 in the air around the system would have that profound effect on pH. But mostly the fact that my once stable pH started dropping without me changing anything outwardly that I could attribute it to. So I was looking for an explanation or factors that I have overlooked. I wanted to make sure that the elevated levels of CA and Mg were not involved in the pH drop (thanks you Holmes-Farley for putting that to rest). I think I am going to make an attempt to inject some more outside air to try and drive more CO2 out of the water. Besides dealing with the bubbles, I do not think there is a downside. Does anyone have an opinion on constant drip of Kalk vs larger intermittent additions. Might this have any effect?

 

[SaltyTwigs]

When did you start using outside air for the skimmer? Adam at Battlecorals recently warned me about issues with pollen as a carbon source on one of my setups, pulling air from outside. I added a 5 gallon diy bucket filter with a HEPA shopvac filter to my system to try to avoid any issues. Not sure if this could truly cause issues but Randy I am sure would have an opionon on it.

 

[Dburr1014]

When did you start using outside air for the skimmer? Adam at Battlecorals recently warned me about issues with pollen as a carbon source on one of my setups, pulling air from outside. I added a 5 gallon diy bucket filter with a HEPA shopvac filter to my system to try to avoid any issues. Not sure if this could truly cause issues but Randy I am sure would have an opionon on it.

I also have a small filter with carbon on my intake. Carbon incase anyone sprays a bug aerosol or the like.

 

[Dburr1014]

Seems like you have a similar circumstance to mine. yes I have a sump under DT, located in basement, along with monitor. I use a 5 gallon reservoir with saturated kalk (measured by conductivity) that I have on a continuous dose. I guess my original question arose from the idea that CO2 in the air around the system would have that profound effect on pH. But mostly the fact that my once stable pH started dropping without me changing anything outwardly that I could attribute it to. So I was looking for an explanation or factors that I have overlooked. I wanted to make sure that the elevated levels of CA and Mg were not involved in the pH drop (thanks you Holmes-Farley for putting that to rest). I think I am going to make an attempt to inject some more outside air to try and drive more CO2 out of the water. Besides dealing with the bubbles, I do not think there is a downside. Does anyone have an opinion on constant drip of Kalk vs larger intermittent additions. Might this have any effect?

I don't see any downside to having more air.
My co2 monitor will sometimes go in the 800's just hanging around in that room. With guests, higher.

 

[Key Largo]

When did you start using outside air for the skimmer? Adam at Battlecorals recently warned me about issues with pollen as a carbon source on one of my setups, pulling air from outside. I added a 5 gallon diy bucket filter with a HEPA shopvac filter to my system to try to avoid any issues. Not sure if this could truly cause issues but Randy I am sure would have an opionon on it.

Ive had the outside hose to the skimmer for a couple years. actually disconnected it a couple times when pH was going over 8.4. Where the intake is located I dont believe pollen would be an issue, but bugs have been. I put a piece of sponge over the opening.

 

[Treefer32]

I've posed this issue as well, with my 340 gallon system. I still think there's something with larger tanks, age, and PH. I have the exact same issue as you with some differences. 1. I ran Vodka for a year. 2. My ph from when I first setup the tank stayed in the 8.1 at night up to 8.4 during the day for the first 3-4 years. Then something happened. I replaced my PH probe thinking something was wrong with the probe. And PH was still low at 7.6 at night and up to 7.8. It was almost overnight that my ph stopped going above 8.0.

I don't know the biological processes enough to understand if there's something continuously producing CO2 in my water. Are there pockets of CO2 creation? Bacteria strains that appear after 3-4 years of operation? I've barely gotten my PH up over 8 in the last 3 months. To do so, I had to do a lot:

1. Stop all vodka dosing completely!
2. Ran my skimmer hose to my air exchanger intake vent to pull in some outside air
3. increased baked baking soda dosing (since stopping vodka dosing, coral uptake of alk has significantly increased going from dosing 40 ml per day of baked baking soda to 240 ml per day of baked baking soda).

I have 3 near adults in 3200 square foot house. I don't know how much CO2 a human generates, but everyone I talk to locally, doesn't believe that 2-3 adults can produce that much CO2 in this much space to keep PH that low. I don't even have a dog or cat or any other pets. My wife has a ton of house plants, that should actually remove some of the CO2.

Some of my neighbors have had radon detected in their basements the largest amounts coming from where the sump pump (low point in the basement) is placed. My sump and aquarium are less than 10 feet from my sump holes.

I don't know if something like Radon, or something in my furnace room, EM Fields from my electrical panel, or something biological inside the tank. Just seems odd, that just 3 years ago I feared my ph getting too high, then after a year of vodka dosing and adding denitrification processes, now I can't get my PH back over 8.0. Something semi permanent happened, and I have no idea what it is.

I know people think I'm crazy for thinking this. But, there's something strange going on in the neighborhood!

 

[Rybki]

I'm kinda hoping that there is some chemistry interaction that I'm not understanding that may be the problem. 6 YO 135 gallon total volume with sump. Skimmer connected to outside air via hose. Kalk dosed separate from ATO. Also dosing Acropower and BRS general adjustment magnesium. Daily additions of DIY NoPox and occasionally LaC (Phosphate RX) to keep phosphate in check. I have 10 Fish, including an adult sized Hippo and Flagfin Angel. Mixed reef with Leathers and Montis and Acros. Great Monti, Chalice growth, moderate/slow Acro growth. I feed DIY frozen melange equivalent to 3-4 cubes a day. Salinity 1.026 (pinpoint salinity monitor for conductivity) 25 gal per month water change with reef crystals.
The situation is thus, been dosing Kalk since tank inception. For last three years pH was 8.2-8.4 (pinpoint, calibrated every month) measured in sump. I only test Alk and Po4 (average .12) regularly, Mg, Nitrate (average 15), Ca occasionally. pH stared dropping to where i can no longer keep it above 8.0 and it fluctuates down to 7.6-7.7 at night. So of course I tested all parameters. I found that my Ca was over 500 and Mg over 1500. I had my Kalk dosing 2.2 ml per minute to keep up with Alk demand (which is always higher than CA demand. Alternately I would add some liquid baking soda to make up for Alk deficiency. I was keeping my Alk at 8.0. So I was pumping in a large amount of Kalk and my pH was still decreasing. Since taking new readings showing elevated levels of CA and Mg I cut back my Kalk additions and Mg dosing until those levels come back in line. To compensate for Alk demand in the meantime I have been adding liquid soda ash instead of liquid baking soda, as per Mr. Farley articles saying that is the preffered additive of the two for tanks with lower pH. Im also using it to slowly bring my alk up to 9.0. The condition of my inhabitants is ok, I am usually of the school that plenty of tanks run at that pH, so don't chase numbers. But in my case the numbers WERE higher ansd stable for a long time and then started dropping. I thought Kalk additions would always keep my pH at elevated levels. Thats why i'm wondering if there is not some chemistry imbalance point I am missing.

 

[Rybki]

Did you change brand of kalk recently,
Or perhaps reactor isn’t air tight or kalk powder gets exposed to oxygen and loses
potency. Even small oxygen exposure reduces kalkwasser PH