Dosing vs. quality salt

[FragIt Dan]

If you can maintain your Ca within ~20 ppm and dKh within a degree with water changes alone, they would be the way to go. This is not typically possible with reef tanks as others have mentioned. As your coral load increases, the draw on your major elements increases and so you begin to need to dose in between water changes. In the meantime, a lighter coral load might (i.e.) only draw your Ca down 10ppm/ week. A good salt might have a Ca level of 450ppm, so a 20% weekly water change would keep your Ca levels from dropping below ~400ppm. I lose about 20ppmCa/day so am at a point where daily dosing is too infrequent (dosing pumps take care of things now). With increased coral load, water changes will eventually not keep up with major element requirements. When you reach that point will be determined by your testing of parameters.