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 though plenty of excess kalk was still present and the mixing was occurring 24x7. I thought that being non-pressurized, and dosing fairly slowly, the solution must be getting weakened by being exposed too long to CO2 at the surface. The surface always had a layer of calcium carbonate crystals, but the rotating shaft and overflow elbow always still had a small air gap. So I switched to the Geo as it is sealed and in theory, should not easily allow contact with air containing CO2.
What I have found is that the solution in the Geo also gets progressively weaker even when large amounts of excess kalk remain in the reactor. I had a 1 minute mixing cycle run every 12 hours, which I extended to 10 minutes to see if a longer mix would help. Nope, no difference in saturation, though it did result in a lot more undissolved kalk getting trapped by my settlement stage that allows me to dose continuous even after and during mixing cycles.
I am wondering if kalk may contain particles that are easier to dissolve and ones that dissolve less easily. Whenever I add fresh kalk to the reactor I always hit 10.3 mS/cm, but that is as good as it is going to get. Each day after that, the high points (after a mix cycle) and low points (before a mix cycle) both get progressively lower. Going way overboard on the quantity of kalk seems to slow the slide somewhat, but not to the point where it seems worth it. After a week, I am still going to be looking at highs being in the 70's and lows being in the 50's, even with an inch of undissolved kalk in the reactor.
This can't all be calcium carbonate precipitated from the solution after getting enough CO2 to precipitate out can it? I realize the incoming water will have CO2, but it can't be that much I would think. My guess on this is that the easy to dissolve particles dissolve first giving the initial saturation and then the next 'level' of particle dissolves, but less easily, and there are less of those, so saturation is not guaranteed unless I go way overboard on the kalk. Once those are used up, then the next particles that are even harder to dissolve are used, resulting it less than saturation.
What would the factor be that makes these particles less easy to dissolve? Could it be that they are less able to dissolve in kalk solution that is already partially saturated? Perhaps they are not able to dissolve as easily because of the high PH of the solution? The next time I am ready to dump the excess kalk and re-fill, I hope to try a test. The reason I would do this, dump and re-fill, is because the saturation is not able to get close to full saturation after a mix cycle. It might only hit 60 - 70%. Instead of dumping the reactor contents, if I were to siphon off the liquid and retain the layer of kalk sludge on the bottom and then re-fill it with RODI and see if it can get back to saturation, then that would suggest they are not able to dissolve due to the saturation of the solution they are being mixed in. Although it still could be PH related, even with that test (if successful). They only thing that would be known for sure, is that the kalk sludge could still be dissolved, it just need to be mixed with fresh RODI exclusively.
Has anyone else noticed this?
Dennis
What I have found is that the solution in the Geo also gets progressively weaker even when large amounts of excess kalk remain in the reactor. I had a 1 minute mixing cycle run every 12 hours, which I extended to 10 minutes to see if a longer mix would help. Nope, no difference in saturation, though it did result in a lot more undissolved kalk getting trapped by my settlement stage that allows me to dose continuous even after and during mixing cycles.
I am wondering if kalk may contain particles that are easier to dissolve and ones that dissolve less easily. Whenever I add fresh kalk to the reactor I always hit 10.3 mS/cm, but that is as good as it is going to get. Each day after that, the high points (after a mix cycle) and low points (before a mix cycle) both get progressively lower. Going way overboard on the quantity of kalk seems to slow the slide somewhat, but not to the point where it seems worth it. After a week, I am still going to be looking at highs being in the 70's and lows being in the 50's, even with an inch of undissolved kalk in the reactor.
This can't all be calcium carbonate precipitated from the solution after getting enough CO2 to precipitate out can it? I realize the incoming water will have CO2, but it can't be that much I would think. My guess on this is that the easy to dissolve particles dissolve first giving the initial saturation and then the next 'level' of particle dissolves, but less easily, and there are less of those, so saturation is not guaranteed unless I go way overboard on the kalk. Once those are used up, then the next particles that are even harder to dissolve are used, resulting it less than saturation.
What would the factor be that makes these particles less easy to dissolve? Could it be that they are less able to dissolve in kalk solution that is already partially saturated? Perhaps they are not able to dissolve as easily because of the high PH of the solution? The next time I am ready to dump the excess kalk and re-fill, I hope to try a test. The reason I would do this, dump and re-fill, is because the saturation is not able to get close to full saturation after a mix cycle. It might only hit 60 - 70%. Instead of dumping the reactor contents, if I were to siphon off the liquid and retain the layer of kalk sludge on the bottom and then re-fill it with RODI and see if it can get back to saturation, then that would suggest they are not able to dissolve due to the saturation of the solution they are being mixed in. Although it still could be PH related, even with that test (if successful). They only thing that would be known for sure, is that the kalk sludge could still be dissolved, it just need to be mixed with fresh RODI exclusively.
Has anyone else noticed this?
Dennis