So I have never had a sump/refugium before as the title says. However, I'm looking to add a 30g tank to my 90g display tank. In my display my main focus is, other than the fish, are the different macro algae that I have. I wanted to originally make the 30g a separate grow out tank to hopefully sell macro frags and make my hobby somewhat fund itself lol. But, the idea of making it one large refugium so that I can increase water volume and have them on opposite light schedules to avoid pH swings has grown on me. I've always only had HOB filters because they're cheaper, work well for me, and I have no clue how to plumb tanks. I'd like to use a HOB overflow so I'm making this post looking for advice, tips, suggestions, etc. Any recommendations for which HOB over flow to get? Have any good/detailed videos or websites to check out for this? Any and all info would be greatly appreciated. Thanks!