I'm in the yacht business- and of 12, yes 12(!), water softeners that are offered only one really works and has an incredible warranty.
will put you on to their site, and their toll free # is 1.888.493.8776
The one you put up for Boji is a piece of garbage with no warranty, sold at West Marine for about $200 and is the fastest way to get rid of an extra $200 without going to a casino that I've found.
The Wet Spot Plus was the right size for what we use it for, and it built like it'll last forever, and recharges properly, where the others use a pre-filter for recharging, this one has its own "recharger" and works properly.
A quick walk down any dock in a nicer high end marina will assure you that this is the right one- it appears to outsell the rest by about 10 to 1, and asking any user will further put your mind at ease...
Their warranty is 12 years, and I've never seen one with a problem...
Washing a boat down with water that contains white calcium, will mar the surface- so what do you think it does to aluminum? Most boats are white- we have to deal with washinga "mirror" so prevention is 90% of the job.