I'm currently having a 8ft long by 4ft wide and 2ft deep freshwater tank built for me, which will include a 6ft by 2 ft sump. I've been doing some research into sump set ups and I've come across the term refugium. It's my understanding this is a tank within the sump where you can keep microalgae. How ever I'm finding it difficult to get information on what exactly macroalgea is. I was hoping someone here could give me some information on it. Also wondering if I would be able to keep shrimp in here as I've always wanted to keep shrimp.