Thanks for the info and clarification.
My setup as follows: I dose ~2L/day via Avast Kalkreactor. pH probe calibrated > 6 months ago.
pH 11.9, --> Add 4 heaping Tbsp. pH --> 12.5 (Day 0)
pH 12.4, Day 5
pH 12.3, Day 16
pH 12.2, Day 18 (rapid pH drop begins...)
pH 11.8, Day 24 (Significant slurry still at bottom of reactor. > 1")
Interesting that I shouldn't trust the visual observation of the reactor to determine the potency of the limewater and just top off every 2 weeks. Data is very similar for 2 cycles of Kalk refill.
I see I am a few months late to the party but I wanted to add similar observations using the same kalk stirrer. My measurements are based on a conductivity probe instead of a pH probe.:
I add 3 liters of kalk topoff daily using a 50 ml/day BRS Top Off Doser - additions are spread out to 125 ml per hour, for 24 dosings per day.
1. On Day 1, I add 1/2 cup of kalk powder to the reactor and Cond reads about 5.3 (I can get a good calibration at 53.0, but I find the readings are not very good at these lower ranges). I have measured calcium of the clear water using a Seachem Calcium test kit and I usually get a reading around the 600-700 ppm range...below saturation but good enough for what I need.
2. On Day 2, Conductivity has dropped to +/- 3.0. Seachem Calcium usually indicates 500-600 ppm range.
3. On Day 3, Conductivity is around 2.5 and calcium is testing around 400-500 ppm.
4. On Day 4, Conductivity drops to 0.0; I find and it will not make readings below 1.9. At this point calcium tests around 400-500 ppm.
My personal observations is the Avast Kalkstirrer simply does not disturb the kalk slurry sufficiently to promote good mixing at the bottom of the chamber. Secondly, the fresh RO discharge port is too high in the chamber to promote redistribution of the calc slurry. I used to run an AquaMedic kalk stirrer and I am thinking about going back to that design. While it does not have a probe port (one could be modded in I suppose), I recall visually seeing the kalk slurry rise in that reactor because the RO injection point was near the bottom. The stirrer was more robust in the AquaMedic unit so it better promoted a saturated solution.
I am also contemplating going to a pump based reactor. With an Apex controller, I can easily put in the fail safes to prevent dosing over saturated kalkwater to the tank.
My final comment here is that I had a hard time searching for kalkwasser saturation issues with kalk stirrers and I find a lot of people just state kalk reactors as a waste of money and to just make the saturated solution and put it in your ATO. There is a really good reason I do not do this. I do not believe kalk should be added to the tank based on your evaporation alone. So if I add my 3 liters of kalk and I still need more water because the evaporation is high that day, I want to top off any excess with straight RO/DI. This is the only way I can monitor and control my daily Alk/Ca additives. So this approach would require two ATO containers and I do not have space for that in my stand...although I suppose I could replace my 10 gallon ATO with two 5 gallon units. Perhaps that is my Plan C.
