Kalk not working as expected

[vtecintegra]

I started dosing kalk, from 8pm to 7am, to help with pH. pH has been running from a low of 7.7 at night, to a high of 7.9 during the day, on average. My goal was for kalk to eliminate the low dip at night. Instead, it looks like it did the opposite and eliminated the high peak in the day. Probe is new and was calibrated. House is new and CO2 is high. I'm in Florida so the house is closed most of the year. In the winter when I can open the house up, pH is much higher. Here is a chart for the last several days. The left area with the peaks and valleys was without kalk. The area to the right is with it. I perplexed with what's going on.

 

[Randy Holmes-Farley Verified Community Expert]

Are you measuring alkalinity? What is it? Higher alk will tend to reduce the swing in both directions.

 

[dwest]

Agree with Randy. Also if your probe is very new, like a couple weeks or less, you should calibrate again after a couple weeks of use. And, if there is someone else in the house, you will notice it with pH. The pH of my tank, VERY roughly, drops about .1 pH point per additional person.

 

[vtecintegra]

Alk has went from 7.7 to 9.0. Currently dosing 1/2 gallon of saturated kalk to 125 total gallons overnight. Coral demand is relatively low with a half dozen hammers and frogspawn, a couple frags of stylo, and some soft corals. Thanks Randy: higher Alk explains why the swing is tightened. Wasn't aware of that.

I'm going to order calibration packets. I got a new Apex with new probe a couple months ago, and immediately calibrated it. Since then I seem to be averaging .1 less. Last Apex was generally showing 7.8 to 8.0. I could get 8.2 with the house open.

CO2 is definitely a problem. 5 people, a dog, and a cat. House is a couple years old and tightly sealed.

 

[Dennis Cartier]

My guess would be the change in your parameters upset your coral and slowed their growth temporarily. Once your alk stabilizes they will return to growing and your peaks will return.

Dennis

 

[dwest]

Alk has went from 7.7 to 9.0. Currently dosing 1/2 gallon of saturated kalk to 125 total gallons overnight. Coral demand is relatively low with a half dozen hammers and frogspawn, a couple frags of stylo, and some soft corals. Thanks Randy: higher Alk explains why the swing is tightened. Wasn't aware of that.

I'm going to order calibration packets. I got a new Apex with new probe a couple months ago, and immediately calibrated it. Since then I seem to be averaging .1 less. Last Apex was generally showing 7.8 to 8.0. I could get 8.2 with the house open.

CO2 is definitely a problem. 5 people, a dog, and a cat. House is a couple years old and tightly sealed.

I have been doing this a long time and, as much as I like to see my corals grow, I try not to worry about low pH. Good luck.

 

[Plandauesq]

Following up on this thread, I am in Florida as well and have the exact same issue. Can someone please help me figure out how to raise my pH. I am dosing kalk via a kalk stirrer daily. With the windows closed, my pH ranges from 7.6 - 7.8. With the windows open, I range from around 7.8 - 8.05. But I obviously am trying to shoot for higher, as I have an SPS dominant tank. My Alk is at 8.9. Any help here would be very much appreciated!!!

 

[Ultra Aquatics]

I would look into a co2 scrubber, this has made the biggest difference in my systems. Kalk helps but it can take a lot to affect ph.

 

[Plandauesq]

I would look into a co2 scrubber, this has made the biggest difference in my systems. Kalk helps but it can take a lot to affect ph.

I have a co2 scrubber, but it only really works if I also keep a window open. I live in South Florida, so that makes it kind of not practical. My system is 300 gallons btw.

 

[Ultra Aquatics]

I have a co2 scrubber, but it only really works if I also keep a window open. I live in South Florida, so that makes it kind of not practical. My system is 300 gallons btw.

I set mine up to recirculate through the skimmer cup. My main system is 400g , I was up to dosing 8000ml a day of regular saturated kalk before the scrubber and ph didn’t change much.
Now I am dosing about 2000ml a day of kalk slurry in addition to the co2 scrubber. I went from ph of 7.8-8.0 to 8.1-8.4. My system is pretty heavily stocked with acropora though.

 

[Plandauesq]

I set mine up to recirculate through the skimmer cup. My main system is 400g , I was up to dosing 8000ml a day of regular saturated kalk before the scrubber and ph didn’t change much.
Now I am dosing about 2000ml a day of kalk slurry in addition to the co2 scrubber. I went from ph of 7.8-8.0 to 8.1-8.4. My system is pretty heavily stocked with acropora though.

I am using recirculating CO2 through skimmer as well. What time of day are you dosing the kalk?

 

[Ultra Aquatics]

I am using recirculating CO2 through skimmer as well. What time of day are you dosing the kalk?

I run it 24hrs. I’m using slurry now though, much more potent

 

[Plandauesq]

I set mine up to recirculate through the skimmer cup. My main system is 400g , I was up to dosing 8000ml a day of regular saturated kalk before the scrubber and ph didn’t change much.
Now I am dosing about 2000ml a day of kalk slurry in addition to the co2 scrubber. I went from ph of 7.8-8.0 to 8.1-8.4. My system is pretty heavily stocked with acropora though.

How did you determine how muck Kalk to dose? Also, how often do you change out the CO2 media?

 

[Ultra Aquatics]

How did you determine how muck Kalk to dose? Also, how often do you change out the CO2 media?

I just started real slow and worked my way up. I also use a calcium reactor and 2 part so I backed those off and increased the kalk.
So far I’m replenishing co2 media every 3-4 weeks.

 

[Plandauesq]

I just started real slow and worked my way up. I also use a calcium reactor and 2 part so I backed those off and increased the kalk.
So far I’m replenishing co2 media every 3-4 weeks.

I cannot get my pH higher than 8.1, even with the CO2 scrubber. What am I doing wrong?

 

[Ultra Aquatics]

I cannot get my pH higher than 8.1, even with the CO2 scrubber. What am I doing wrong?

What’s your alk at?

 

[Plandauesq]

What’s your alk at?

8.87

 

[homer1475]

I have been doing this a long time and, as much as I like to see my corals grow, I try not to worry about low pH. Good luck.

Couldn't agree with this more.

I really hate BRS put out the videos on PH. Now all the chem section is, is multiple question on how to raise PH to that magical number. Remember when we could care less what PH number we had?

 

[arking_mark]

A couple of thoughts here:

1. Kalk is for balanced Ca/Alk dosing. pH boost is a nice side effect. If you dose kalk for pH you're likely to spike your tank.
2. House CO2 is very dynamic and can change drastically over hours and days depending on many factors. A longer observation period may provide more insight.

 

[EMeyer]

Couldn't agree with this more.

I really hate BRS put out the videos on PH. Now all the chem section is, is multiple question on how to raise PH to that magical number. Remember when we could care less what PH number we had?

Absolutely.

Not to mention which, the "help with my pH" posts almost always
1. already have normal and appropriate pH (7.8-8.1)
2. ignore the fact that daily swings in pH also happen in the ocean

stable, high pH is not natural or desirable