Start with getting proper test kits. Doing that assures consistent tests.
- Test your Nitrates and Phosphates. Set a goal. Mark target parameters. Go with that. Example.. NO3 5-10 & PO4 0.01-0.04 = Alk 7 - 8.5dkh ---- NO3 10-20 & PO4 0.05-0.1 = Alk 9dkh - 12dkh(if you lose no3 or po4 and need to drop alk, allow alk to drop VERY SLOWLY). If you have low nutrients and high alk, bleaching can occur. If you have high nutrients and low alk, browning can occur. You can increase no3 and po4 yourself but most times its present from feeding or rock/sandbed leaching nutrients.
- Begin testing all mixed batches of saltwater for water changes. You need to do this for every water change. Why? Because, salt can settle in mysterious ways. Causing things to separate and mix up. Sometimes having more mag or alk in different areas of the dry salt box/bucket.
- Match fresh mixed salt (for water changes) to tanks alkalinity. If by chance fresh mixed salt has higher alkalinity, do some math, cut water change to a smaller amount, or purchase a lower alk salt mix.
- Daily alkalinity testing morning and night for 2 weeks can give you a good idea of consumption. If you start adding more coral or if they grow to larger colonies later on, begin testing again. Dose accordingly.
Most important test for water changes is alkalinity. However if you are having fluctuating magnesium in DT or display tank, then incorp. mag testing to that water change regimen.
Keep doing research. All your answers are here in the forums
That's a big jump from yesterday? Try not to go overboard with alkalinity. Levels really depend on nutrients. But you're headedin the right direction. 
