I haven't seen this discussed, but maybe I'm just bad at searching. Bear with me... So if you're using limewater/kalkwasser/calcium hydroxide for your alkalinity and calcium, it helps raise the pH and is cheaper than using 2 part. The main complaint about it that I've seen (besides the possibility of nuking your tank if you don't have it set up properly and don't have safeguards) is that eventually your need for alkalinity will be higher than the amount of saturated limewater you can add to replace evaporated water. A common solution to this is to add vinegar to the kalkwasser reservoir to increase the solubility and get more alkalinity and calcium per volume of limewater. The downside to doing this is that you lose some of the pH boost and you're adding carbon to your tank, which you may not want. Plus there's one more thing you have to buy and measure out (vinegar). A lot of us have an AWC system, which seems to provide the perfect solution. If you've got a AWC system set up, you probably already check your salinity fairly regularly. If your salinity is high, you can just drop the amount of new saltwater coming in and your ATO will slowly dilute out the salt. If your salinity is too low, you can add new saltwater a little quicker and your ATO will automatically slow down which slowly concentrates your water. The problem with adding more kalk than your evaporation rate is that your salinity would drop and your sump would overflow. But, if you've got an AWC system running, you could pull enough extra water out to match the extra kalk you're adding. The only problem would be that your salinity would slowly drop. If you mix up your new saltwater to be more concentrated than your display tank, though, you need less volume of new saltwater to replace the salt you are removing through the AWC system to make room for the extra kalk. Hopefully that all makes sense. That's what I'm doing now and it seems to be working. Just haven't seen anyone mention that this is an option anywhere. At some point, I assume the saltwater in my brute trashcan would have to be so concentrated that stuff would precipitate out, so there's still probably a limit, but this definitely seems to be a way to stick with kalk for longer without having to mess with vinegar and without getting more dosing pumps to start using 2-part.