Check it out, an article by @MarineDepot https://blog.marinedepot.com/2019/03/how-to-set-up-a-refugium-harvesting-macroalgae-to-control-nitrate-and-phosphate.html?fbclid=IwAR3YYT1vYyKaiMASe9Z4BXLYtZoEz4erZvmUghiWInlGi6vao9ZRSVRVa54