Twenty plus years ago when I kept fish I always had a diatom filter which was used as a supplement filter used for water changes and cleaNing the sand and scrape the glass. Plus Vortex claimed that their filter can filter out ich and other parasites . Well when starting back up again one of the first things I looked for was a diatom filter but to my surprise it was hard to find one. Actually just found one from Marineland and had to go to a pool supply store for the DE powder. So my question is why are diatom filters more popular in the fish keeping hobby


