I heard this advice from a guy at LFS. Yes, he is just a guy from a LFS. But
is this true?
Yes, but unless you have a lot of carbon in the filter, it probably won't make
a big difference.
I read activated carbon absorbs medication so it is wise to take it out when
you add anti-ich
Yes. Always remove carbon when medicating the tank.
It's just that it's a pain to remove/ put on carbon in your filter whenever
you drop some
medication in the tank
Just leave the carbon out. You don't need it.