Question on dosing trace elements

[ghellin]

I have a 58 gallon sps/lps reef that I do weekly 10% water changes on using only salinity salt. My parameters are pH 8.2, salinity 1.026, Alk 9, mag 1350, calcium 450-500, phosphate 0, nitrate 0 and so on. with this I get great growth and very nice color, I was wondering since I have never dosed trace elements or anything else really if I need to start or is my weekly water change supplying what I need?

Thanks,
Greg