Does a skimmer remove saltwater?

[Cal_stir]

you should test for everything you dose to ensure you are not over or underdosing but the best way to replenish trace elements is with water changes because the elements are in the proper levels and you can't overdose, if you dose trace elements then you will probably get the concentrations too high over time and you can't test for all the trace elements. a 10% monthly water change would suffice.