[Myka]

What speed is your dosing pump? I use dosing pumps just for calcium and alkalinity. Magnesium is easily supplemented by adding a bit extra to weekly waterchange water.

I just started dosing limewater on my SPS tank. I haven't used it for years, but it is great stuff. I don't like adding it to top off water because top off volume varies from one week to the next which means limewater dosing will vary. I prefer to use a doser.

I'm using a Drew's Doser that runs 1.6 mL per minute which means the maximum it can dose in 24 hours is 2300 mL. So that limits things. Saturated limewater is 2 tsp per 1 gallon of RODI water. If you add 45 mL vinegar you can increase that to 3 tsp per 1 gallon of RODI water. Although vinegar is something that should be added in slowly increasing increments and monitored closely as vinegar is a carbon source so you can get excessive bacteria growth (which can deplete tank of oxygen).

So, there are a few options for you to consider. Also, if you're going to dose limewater I would suggest you monitor pH with a digital pH meter (not drop tests) since limewater has the ability to raise pH drastically and lethally.