I’ve always ran skimmers. 13.5, 60 gallon (in the sump so almost necessary) and that’s about it. I now have a 25g because it is more practical and wondering if I absolutely need one. My tank seems to be doing great. Been running for about a month or so now now granted it was already cycled when transferred but, from what I see it looks as I don’t need one. Looks can be deceiving sometimes tho so let me know what y’all think!