Hey Dmitri, You should also paint any metal fittings or clamps that are directly above all open water areas. As zinc corrodes (and galvanized is just bulk zinc hot dipped) it will flake and drop off. If it's over the tank or sump guess where it goes.
I used these pipe clamps and stainless threaded rod for suspending my drain lines out of the overflow box. Between those over the sump and some hinges over the display I was getting elevated zinc and some other elements. Luckily I caught it before anything bad happened. I bought new clamps and painted them with a few coats before putting them back in place. I see a lot of metal hanger clamps that will be over your tank, better to take care of it now.