A holding tank aeration system will cure it....PROVIDED it runs continuously 24/7/365 (except of course during winter or other extended layup) and is also otherwise maintained according to directions.

However, a holding tank aeration system will NOT cure odor inside the boat...because the tank, unless it's leaking, is rarely if ever the source of odor inside the boat...because odor from inside the tank has only place to go--out the vent.

As for the cost of the Groco Sweetank system, it will pay for itself fairly quickly because when installed, operated and maintained according to directions, no other tank product(s) should be needed. (Yes, the pump is "explosion proof." Here's the complete manual for it: http://www.groco.net/SVC-MAN-07/Sec1/pdfs/STK.pdf