I am looking to change my substrate to sand soon. I am likely to go with Argos play sand. I understand it needs thouroughly washing first.
My question is, is it possible to add the sand with the fish in the tank, or will I need to remove them?
My question is, is it possible to add the sand with the fish in the tank, or will I need to remove them?


You do need to keep the filter media wet, but wrapping it in a plastic bag, or taking the media out of the filter into a bucket will be fine.