hmm, lets see. I've used both the refugium and the GFO method successfully and tried carbon dosing unsuccessfully.
Refugiums are great, but take a lot of space for the job they do. I'm talking like as much square footage as you can get. I have a 65 gallon tank with a 38 gallon refugium which has 3.0 sq ft of ground space completely covered with caulerpa and its was not enough to export nutrients. If I were to guess, I think I need to double up on the algae growth to balance food in and algae export out, so that means 6.0 sq ft of area to grow algae. That's a lot of lighting also, requires at least 3 T5 bulbs, 2 where not enough and that's an extra fixture cost. I have a large fish load, but if I had only like 1 fish, 3 sq ft is enough.
GFO is very compact, and with the 5 gal bucket price, I'm using about $7 per month in my reactor.
Plus I also have a denitrifier from aquaripure which works well and these 2 devices seem to out perform my refugium significantly.
Bio pellets seem like a good idea of exporting bacterial biomass. I'm not experienced with them, though I have tried similar vodka dosing but these methods require a very good skimmer.
If I had a top of the line skimmer, didn't have my denitrifier or my GFO reactor, I'd probably go with bio pellets in a RELIABLE reactor or some other method of vodka carbon dosing, long term as this is pretty inexpensive in the long run. Then I could run a small refugium on the side for biodiversity.
