0 Nitrate 0 Phosphate Refugiums

For those of you who have achieved superior nutrient export via refugiums such that your test levels are always near zero, how are your refugiums set up? What is the methodology behind your setup? Such as substrate, size, flow rate, lighting schedule, macros, skimmerless? , how long did it take to become viable?

The more detailed and informative you can be the better. I believe it's our responsibility as reefers to provide as stable and beneficial an environment for our beloved hobby as is within our means. At the root of our hobby is understanding and so I hope to collect some useful insights here from your experiences.