I know I asked about this at one point before but I can't find the thread sorry for being redundant...

Willy bruised himself again and I can't remember what I need to do, like Melafix or anything...I don't want him to wind up with anything nasty like an infection under his scale or something, since it doesn't look like he'll loose the scale this time. He has a blue-black area underneith one scale on his side, and he's a little ouchy in that area (flinches when I run my hand over it). Looks like he tried to muscle the filter out of the way...guess I get to construct a new one he can't do that to. Water params and everything are fine, it's just that one spot on his side...no swelling either.

Keeping his water pristine is the best way to heal a scratch You can also raise the salinity to 0.1% to prevent any secondary infections but clean water is all he needs if it's just a minor wound

I can't raise the salinity in the tank (breeding apple snails), so would a salt dip work?

nah...he doesn't need a salt dip Why not try an iodine swab instead?Dip a q-tip in iodine and swab her scratch gently being careful not to get it on his eyes,mouth and gills.You only have to swab once....