Kalkwasser Dosing: dKH going up by not pH

[Adamantium]

Hi all,

I’ve been dosing a Kalk solution every night via DOS, and my dKH has steadily climbed from
8.0 to 9.5 over the past few weeks, but my pH still sits between 7.8 and 8ish.
Any ideas? Should I put a power head in the dosing container so the solution is constantly in suspension?

Thanks!

 

[piranhaman00]

Your pH will only momentarily go up, if you raise 1.5 dkh over a period of weeks you will not see any pH boost.

 

[KStatefan]

What is your alk demand of your tank?

 

[Garf]

Hi all,

I’ve been dosing a Kalk solution every night via DOS, and my dKH has steadily climbed from
8.0 to 9.5 over the past few weeks, but my pH still sits between 7.8 and 8ish.
Any ideas? Should I put a power head in the dosing container so the solution is constantly in suspension?

Thanks!

I wouldn’t push the Alk up to benefit pH. I’ve tried it, won’t be trying it again.

 

[Randy Holmes-Farley Verified Community Expert]

pH is driven by alk and CO2 in the water. Nothing else.

Adding kalkwasser tends to consume CO2 in the water, raising pH, but if the water is well aerated with higher CO2 air (such as indoor room air), then that can override the pH effects of the aklkwasser.

More fresh air to the room, or aerating with low CO2 air (outside air to skimmer inlet or CO2 scrubber on skimmer inlet) can help raise pH.

 

[Adamantium]

Your pH will only momentarily go up, if you raise 1.5 dkh over a period of weeks you will not see any pH boost.

What do you mean by that? Momentarily as in for a few hours? Because the DOS is dosing slowly over 12 hours.

 

[Adamantium]

pH is driven by alk and CO2 in the water. Nothing else.

Adding kalkwasser tends to consume CO2 in the water, raising pH, but if the water is well aerated with higher CO2 air (such as indoor room air), then that can override the pH effects of the aklkwasser.

More fresh air to the room, or aerating with low CO2 air (outside air to skimmer inlet or CO2 scrubber on skimmer inlet) can help raise pH.

I appreciate the input. I would think that, but we have an air exchanger on the house, and I’ve measured the CO2 level. It sits around 3-400 (whatever unit? PPM?). To top it off, I use a CO2 scrubber.

 

[Randy Holmes-Farley Verified Community Expert]

I appreciate the input. I would think that, but we have an air exchanger on the house, and I’ve measured the CO2 level. It sits around 3-400 (whatever unit? PPM?). To top it off, I use a CO2 scrubber.

Try recalibrating the probe and dosing the aeration tests described here:

http://www.reefedition.com/ph-and-the-reef-aquarium/

The Aeration Test

Some of the possible causes of low pH listed above require an effort to diagnose. Problems 3 and 4 are quite common, and here is a way to distinguish them. Remove a cup of tank water and measure its pH. Then aerate it for an hour with an airstone using outside air. Its pH should rise if it is unusually low for the measured alkalinity (Figure 2). Then repeat the same experiment on a new cup of water using inside air. If its pH also rises, then the aquarium’s pH will rise simply with more aeration because it is only the aquarium that contains excess carbon dioxide. If the pH does not rise in the cup (or rises very little) when aerating with indoor air, then that air likely contains excess CO2, and more aeration with that same air will not solve the low pH problem (although aeration with fresher air should). Be careful implementing this test if the outside aeration test results in a large temperature change (more than 5°C or 10°F), because such changes alone impact pH measurements.

 

[Adamantium]

What is your alk demand of your tank?

About .5-.7 dKH/day.

 

[Adamantium]

Try recalibrating the probe and dosing the aeration tests described here:

http://www.reefedition.com/ph-and-the-reef-aquarium/

The Aeration Test

Some of the possible causes of low pH listed above require an effort to diagnose. Problems 3 and 4 are quite common, and here is a way to distinguish them. Remove a cup of tank water and measure its pH. Then aerate it for an hour with an airstone using outside air. Its pH should rise if it is unusually low for the measured alkalinity (Figure 2). Then repeat the same experiment on a new cup of water using inside air. If its pH also rises, then the aquarium’s pH will rise simply with more aeration because it is only the aquarium that contains excess carbon dioxide. If the pH does not rise in the cup (or rises very little) when aerating with indoor air, then that air likely contains excess CO2, and more aeration with that same air will not solve the low pH problem (although aeration with fresher air should). Be careful implementing this test if the outside aeration test results in a large temperature change (more than 5°C or 10°F), because such changes alone impact pH measurements.

I’ve tried the aeration test in the past and found little to no change in pH. I can try it again, though.

Could it just be that my kalkwasser solution isn’t saturated enough? I added a ton of kalkwasser, but the meter I bought only reads up to 8 ms/cm. So I’m close, maybe even over 10.3, but I don’t know for sure.

 

[Adamantium]

Try recalibrating the probe and dosing the aeration tests described here:

http://www.reefedition.com/ph-and-the-reef-aquarium/

The Aeration Test

Some of the possible causes of low pH listed above require an effort to diagnose. Problems 3 and 4 are quite common, and here is a way to distinguish them. Remove a cup of tank water and measure its pH. Then aerate it for an hour with an airstone using outside air. Its pH should rise if it is unusually low for the measured alkalinity (Figure 2). Then repeat the same experiment on a new cup of water using inside air. If its pH also rises, then the aquarium’s pH will rise simply with more aeration because it is only the aquarium that contains excess carbon dioxide. If the pH does not rise in the cup (or rises very little) when aerating with indoor air, then that air likely contains excess CO2, and more aeration with that same air will not solve the low pH problem (although aeration with fresher air should). Be careful implementing this test if the outside aeration test results in a large temperature change (more than 5°C or 10°F), because such changes alone impact pH measurements.

I’ll recalibrate the probe right now, though. Thanks!

 

[Adamantium]

Well, recalibrated and still sitting at 7.85 right now.

That said, I think it might be a bad probe. I have two handheld meters that are both reading 8.2….

I wish I could manually adjust the calibration :/

 

[Randy Holmes-Farley Verified Community Expert]

I’ve tried the aeration test in the past and found little to no change in pH. I can try it again, though.

Could it just be that my kalkwasser solution isn’t saturated enough? I added a ton of kalkwasser, but the meter I bought only reads up to 8 ms/cm. So I’m close, maybe even over 10.3, but I don’t know for sure.

Little or no change at what pH and with what type of air?

 

[Adamantium]

Little or no change at what pH and with what type of air?

I’ll have to run the test again and get back to you. I just recall it being negligible.

It seems like my pH is elevated, based on the two handheld meters reading 8.2. I’ll get a new batch of calibration solutions and see if I can’t get it closer. Should that fail to help, I think a new probe might be in my future.

 

[Adamantium]

Well, after multiple resets and calibrations, I’m now reading 8.31.

A bit frustrating that it took so much fiddling for such a pricey bit of kit, but at least I got to where I needed to go.

 

[Garf]

Well, after multiple resets and calibrations, I’m now reading 8.31.

A bit frustrating that it took so much fiddling for such a pricey bit of kit, but at least I got to where I needed to go.

That’ll be why the aeration test made no difference then, lol

 

[Randy Holmes-Farley Verified Community Expert]

Glad all is well.

Happy Reefing