The biggest problem with calcium hydroxide is the delivery method, which is almost always the ATO. Auto top-off systems are great at keeping salinity relatively stable, but they're nowhere near precise enough to dose a measured amount of fluid at the same time every day (unless you use a dosing pump to top-off and dose the same amount of freshwater every day). Additionally, because evaporation can vary based on how much your AC runs, how often you have the windows open, how dry the air is outside, etc, an ATO dosing limewater will likely never give you the exact same amount of limewater from one day to another. Plus, if you want to change how much calcium hydroxide goes into your tank, you have to dump your ATO reservoir and mix up a new batch of limewater at a different concentration.
I dose limewater using a dosing pump. Every hour on the hour my tank gets a little bit of calcium hydroxide. My ATO picks up the rest. If my calcium and alkalinity are trending too high, I back down the dose of limewater. If they're dropping, I increase the dose. The only downside to this approach is if your tank uses a lot of calcium and carbonate alkalinity, you might dose so much limewater that you outstrip your tank's need for freshwater. In such cases, the water level in your tank will rise. However, it's pretty apparent when this happens.
