Kalk stirrer loses potency. Potential enhancements?

[Crashjack]

I have my kalk stirrer setup with a pH probe in it. My pH averages 12.4 in the stirrer. I figure as long as it is above 12 that I'll be dosing saturated kalk. I know that it is saturated with dosing and increases that I see if I increase the dosage.

The Geo Reef kalk stirrer is much, much better than the Reef Octopus that I had. Yes it is a little more $$$, but I'd make the purchase again in a heartbeat.

I don't keep a pH probe in my stirrer but wondered, how long do you keep 12+ pH before it gets below that. What I've discovered is, the mods I did probably helped a little, but to get the most out of my stirrer, I have to rinse out and replace kalk every two weeks. I still see degradation of alk after the first week, but increasing the amount of time I dose kalk every day helps to offset. I've also set my kalk to running during the day figuring it should help stabilize alk/Ca throughout the day. I'm just not sure yet if the resulting higher pH is going to cause enough additional uptake to outrun my maximum kalk addition.

My problem is that I'm stuck with this 2-week cycle because my maintenance guy comes every two weeks (I'm handicapped and rely on my maintenance guy to handle all of the "heavy lifting"). If I could clean and replace kalk weekly, I think kalk alone would handle my alk/Ca needs for some time. Right now I could physically do it, but it would take a lot of time, I would likely make a mess, and it would detract from my overall enjoyment of having the tank. I'm working on a better long term solution... dosing with an alk monitoring device, or Ca reactor and possibly adding an alk monitoring device later on. I used a Ca reactor when I was in the hobby years ago, which is why I wanted to avoid this go-round. I've gotten interested in the DaStaCo just because the supposed ease of operation (obviously if all went well). The biggest problem I have with other reactors is trying to reach under the tank to access everything to make adjustments. My hope with the DaStaCo is to mount the powerbar/controller to where I can easily reach it, and make adjustments there, and then the big stuff-- replacing media and the CO2 bottle, preventative maintenance, and so forth would be handled by my maintenance guy.

 

[Raining_Sheep]

Have you noticed any improvement? Im having this same problem. I have an Avast Marine K2 and it works great for the first 2 weeks, then drops off. My theory is when it supplies sufficient Alk the tank starts consuming more, diminishing the effectiveness of the new Kalk. Im currently Dosing the Alk componnent of the Seachem reef fusion to supplement via trident/apex DOS

 

[Randy Holmes-Farley Verified Community Expert]

I would note that by the time you see a significant drop in effluent pH, the potency has dropped a lot. pH 12 is very poorly potent limewater. A drop of 0.3 pH units is about a 50% drop in potency.

Checking the effluent via conductivity is a much better way. Saturated at 25 deg C is around 10.3 mS/cm. Potency is mostly linear with conductivity. So 5.2 mS/cm is about 50% saturated.

 

[Graffiti Spot]

When I use a stirrer that runs the fresh ro water through the kalk sitting in the bottom instead of mixing with the water above the kalk, I don’t have this issue.

 

[DangerDave]

I have an Avast and haven’t had that issue. How much kalk are you Loading it with?

 

[Crashjack]

Have you noticed any improvement? Im having this same problem. I have an Avast Marine K2 and it works great for the first 2 weeks, then drops off. My theory is when it supplies sufficient Alk the tank starts consuming more, diminishing the effectiveness of the new Kalk. Im currently Dosing the Alk componnent of the Seachem reef fusion to supplement via trident/apex DOS

I've had to start running kalk 24/7, and I also started doing two more things: 1) I rinse the stirrer and add new RO and kalk every two weeks instead of just adding more kalk after two weeks, and 2) I programmed my controller to run my stirrer for :45 minutes every hour, creating more "stir" as the blade starts to turn every hour. All of that said, I started looking hard at my alk measurements and realized that over a 3-day span, I was losing .45 dkh like clockwork. It also didn't matter if it was soon after rinsing/adding new RO/kalk or late in the 2-week cycle. I figured the amount of sodium bicarb and Ca chloride I needed to add every third day to keep it steady (e.g. when I run alk tests every Tuesday and Saturday around the same time of day, my alk typically varies .2 dkh or less and remains spot-on a lot of the time). The Avast instructions tell you to rinse out/clean every 4 weeks and then after two weeks, just add new kalk. My hypothesis is that the biggest issue is when adding kalk after two weeks (kalk powder on top of kalk powder), it doesn't saturate well, possibly due to the high pH or near-saturation of what is already in the stirrer. When I went back and analyzed my logs, I found that the alk drop was greater during the two weeks I just added kalk versus the two weeks I emptied the stirrer and re-filled with with RO and kalk.

The bottom-line is, I can no longer maintain alk/Ca by kalk alone unless maybe I was to put fans to blow across the surface of my tank to increase evaporation. My advice is: 1) Rinse and add RO/kalk to the stirrer every two weeks instead of just adding kalk after week two, 2) Do whatever you can to increase the "stir", and 3) Be prepared to include an additional method of maintaining alk/Ca as kalk alone isn't going to maintain it forever.