Try this site. http://reef.diesyst.com/chemcalc/chemcalc.html
it has a calculator to help determine dosing amounts.
Once you have your levels adjusted to the correct levels, you need to determine average daily consumption for your tank.
Basically, you stop dosing and measure the change in levels over a couple days. Divide the change by the number of days between tests and that should give you an approximate
Consumption rate.