Depending on the age of the hose
I would test 'em for odor permeation before attempting to clean 'em out, and if they have permeated, replace 'em. 'Cuz you'll never have an odor-free boat as long as they're in the boat. Fresh water and Odorlos alone would not prevent mineral buildup...neither has any properties to dissolve the crystals. Vinegar does...in fact, repeated doses of it will even get rid of a buildup as severe as yours. Muriatic acid is faster, but a bit too dangerous to handle to use as a regular preventive. As for how long you can leave it in the hoses, I suggest you read--and FOLLOW--the directions for use on the muriatic acid bottle. If the hoses have been neglected, I suspect the tank has been too...meaning there's likely to be a buildup of sludge in it that may or may not have turned to "concrete." If so, and if it's still mud, it can be flushed out by adding a few gallons of water down the pumpout deck fitting (because the water will enter the tank at the bottom to stir it up)...pumpout...repeat...repeat...till the water being pumped out is clean. Do NOT attempt this using the macerator to dump the tank...the sludge will only clog up the macerator. However, if it's turned to "concrete" there is nothing that will dissolve it that won't damage the tank...muriatic acid will not work for this. If the buildup is deep enough to block the tank discharge, your only choice is a new tank.
