Q. (See question above). When taking them to the Mikva, do I have to unscrew the metal cap before I Tovel them?
A. Horav Shlomo Miller’s Shlit’a opinion is that you should, since the water will likely not penetrate through the small holes of the cap of the shaker.
Horav Aharon Miller Shlit’a further added that the space where the cap is screwed also has to be covered by the Mikva waters.
Rabbi A. Bartfeld as revised by Horav Dovid Pam, Horav Aharon Miller and Horav Chanoch Ehrentreu Shlit’a.