There is nothing wrong with a refugium as a tool in the belt to help with nutrient control. However, most people are using sumps with a built in refugium compartment, and while large enough to be productive, they simply aren’t large enough to have a significant effect. Especially if someone has phosphate bound rock and substrate.
To get the impact they would need, they need to scale up, and run a much larger external refugium, a reactor, or a scrubber. Scrubbers are very productive at nutrient export and can outperform the other algae systems in a smaller footprint.
My fuge chamber is 14x10x10 and was packed with healthy cheato. Harvesting weekly. It was a good system but “not enough”
I installed a scrubber with a 6x4x2 growth chamber and was blown away. The cheato all turned white and died. Then…I started getting hair algae ALL OVER in my display. It started growing out of rocks. It grew right out of my sandbed in patches. I would manually remove the best I can from all the random spots it would appear
This was in a sps reef I kept that did not have algae issues prior, but did have high phosphates and nitrates I was trying to reduce.
Now all the sudden my cheating is dead and my display has algae. Until. It didn’t. Over the course of a few months the algae stopped appearing and the phosphates and nitrates went down. Nitrate went to zero. Phosphate went to 02-.03. And the only change I made in this system was install the scrubber. It did take time. About 4-5 months total. But what I experienced was consistent with what I read about scrubbers. The small scrubber I installed was not only equal in performance to the larger cheato refugium, it was stronger and more productive, achieving what the refugium never was able to. I do believe the same results could have been obtained with an external refugium but it would have had to be considerably larger than anything I was willing to add
