Excellent system
And considerably more than "just" an aquarium bubbler. Yes, it's expensive compared to aquarium bubblers...but, unlike aquarium bubblers, it has to survive in a highly corrosive environment AND run on 12v. The pump also moves a LOT more air than an aquarium pump--something like 1.7 litres/min, which is necessary to achieve sufficient aeration to keep the tank aerobic. Too little air and all it does is agitate the anaerobic contents, INcreasing instead of decreasing odors out the vent. Most aquarium pumps only produce a column of air...the Sweetank includes perforated piping to distribute air throughout the tank. To be 100% effective it has to run 24/7/365 (except during winter layup, of course). If you shut it down, allowing the tank to turn anaerobic again, it has to run at least a couple of hours before the gasses forced out the vent are odor free again. The odor gradually decreases, but can be really RIPE for the first hour. In addition, shutting it down can allow any sludge to clog the holes in the tubing. So it's not appropriate for boats that aren't connected to shore power...and IMO, only necessary if passive ventilation above the surface cannot keep the tank aerobic. 90% of boats don't need it...for the other 10%--especially large boats that have large (50 gal+) tanks buried beneath cabin soles--it's worth every penny.
