it appears that the concensus here is that the Octopus skimmer is the one to buy for those of us on a budget. I have a 58 gallon tank with a 29 gallon sump under the stand. I'd like to add a refugium sometime, and have a 55 in the basement that I'd like to pump everything down to. SO, that makes my total potential gallons something over 100 gallons. Should I go with the NW-200 or will the NW-150 do the job. I don't want to use the space if it doesn't matter.