Kalk Stirrer Losing pH potency after a week

[Fallenreef]

I have been using avast kalk stirrer k1 for a while now. I have noticed that no matter how much kalkwasser I add after each refresh, the pH increase in my display slowly decreases each day while dosing the same amount of (continuous drip for 12 hours with a peristaltic pump). What is also weird is that I am still get the increase in alkalinity that I need just without the pH increase in the display. What could be the issue and how can I solve it besides adding fresh kalk every few days. I have attached graph of my alk and pH. I also confirmed the calibration of my ph probes as well. Thank you!

 

[blaxsun]

No idea, but you might be running a bit on the high side (8.6 pH) - so it's possible that your tank is naturally trending down to more normalized levels between 8.1-8.3 pH.

 

[Randy Holmes-Farley Verified Community Expert]

One of the drawbacks to a stirrer relative to a settled reservoir is the challenge to getting saturated limewater. I expect that is the issue even if it’s not showing readily in alk.
There’s no possibility that it can actually be delivering the same alk and less of a pH effect unless there is calcium carbonate sediment present that is getting delivered as a slurry, and it is making its way to the alk test, where it would dissolve and give a false high alk reading.

 

[Fallenreef]

One of the drawbacks to a stirrer relative to a settled reservoir is the challenge to getting saturated limewater. I expect that is the issue even if it’s not showing readily in alk.
There’s no possibility that it can actually be delivering the same alk and less of a pH effect unless there is calcium carbonate sediment present that is getting delivered as a slurry, and it is making its way to the alk test, where it would dissolve and give a false high alk reading.

Thanks for the reply Randy! Is there a way to improve the performance of the stirrer (I already added the zip ties) to get it to be more saturated in the reactor? Thank you

 

[Randy Holmes-Farley Verified Community Expert]

Thanks for the reply Randy! Is there a way to improve the performance of the stirrer (I already added the zip ties) to get it to be more saturated in the reactor? Thank you

Does it stir 24/7 or just intermittently?

 

[Memisis]

What are you using to measure and log DKH in your apex?

 

[Fallenreef]

Does it stir 24/7 or just intermittently?

I am stirring 24/7 and dosing RODI on a dose only at night for 12 hours

 

[Fallenreef]

What are you using to measure and log DKH in your apex?

I am using a trident and a KHG to test for alkalinity

 

[Randy Holmes-Farley Verified Community Expert]

If you are concerned about changes in potency, I'd try to measure the potency, and using conductivity is the most precise and accurate way to do it.

 

[Dennis Cartier]

I was wondering the same thing awhile back and posted a thread on it. Some useful info in it on this issue.

Why is Kalk so hard to dissolve?

I have been using kalk in a reactor off and on for years. I started with an Avast K1 and then moved to a K2. I now run a Geo 8" kalk reactor. I switched from the Avast's after I started monitoring the saturation using an EC probe and found that the reactors would start to lose saturation even...

www.reef2reef.com

I no longer use the Geo reactor in continuous dosing mode. I simply swapped the input and output and use the pump to mix freshly added kalk, then pull from the settled reactor for a few days and then refill with fresh water and kalk and start over. About once a month I dump the undissolved kalk and start afresh.

 

[BanjoBandito]

I just dose enough kalk to hold my alkalinity. I generally focus on the skimmer and scrubber to off gas CO2. With that said, an average PH above 8 seems fine?