The ideal sump/refugium

[Dale]

Just for discussion sake,
If you are looking for an effective refugium/nutrient export system and don't have to worry about space try installing a rain gutter.
Take a 6-8 ft gutter, feed water in one end and have it drain into the sump from the other. Take a role of gutter guard, cut it length ways and weave it back and forth down the gutter like this:



Mount a plant spectrum fluorescent bulb over the gutter, remove the gutter guard once in a while to scrape off the algae and you will have a very effective nutrient export factory.