http://www.advancedaquarist.com/issues/sept2002/chem.htm
http://www.advancedaquarist.com/issues/august2003/chem.htm
here are some starters for the benefits of a refugium.
i have since stopped using a refugium for my 180g reef and have gone full zeovit with slow but incredible results. but zeovit isnt for everyone and i would not recommend it unless you have a lot of time and energy to devote to tank maintenance.
i have a refugium though on my 125g fowlr and it does and incredible job at keeping water nitrates and phosphates low enough to be comfortable for fish only.
research refugium design and mechanics. the old school way of thinking is that a refugium needs to be large or it wont work effectively. the same goes for slow flow. what a horrible concept. a refugium of this design will be nothing more than a smelly disgusting settling chamber.
my refugium is profoundly small at only 3% of total tank volume, has a 70x/hour turnover and no rock, rubble or sand. to say that my refugium grows chaeto faster than rosie o'donnels beard...well, it cant grow macro THAT fast!
why is this design so effective?
the bucket is round...the incoming water flow goes 'around' the bucket interior in a swirl motion...causing the wanted turbulent alternating flow, the water level is very close to the light which also makes the light much more effective as well as efficient to grow the macro. the whiteness of the bucket is also a huge bonus as it reflects light back into the refugium utilizing the light even more effectively.
here is a pic of it. yep it is a 5g bucket! i love laughing cuz the bucket cost $5 and being fancy, i decided to use uniseals at $2.50 a piece. throw a light that costs $8.50 and you have a killer refugium that i doubt few could make more effectively and efficiently regardless of price or design. oh, it took me about 15 minutes to make.
here is a pic of it at the start with a softball sized ball of chaeto:
here it is 3 weeks later (i think...maybe only 2...cant really remember). note there is no light penetrating into the bucket anymore due to the amount of the chaeto growing and blocking the light.