How heavily stocked is your tank? A tank full of SPS or a tightly packed nano for instance dont have the luxury of the dilluted water vollume a conventional tank would have. A frequent water change regiment will add the routine supplements for most tanks that have the larger water/livestock volume ratios.
What do your tests show the levels at? Always better to do dosing in small gradual amounts instead of large once a month dumping sessions when using raw chemicals.
Look at your tests, adjust accordingly to hit your target.