Shotgun meds

Well I am not too surprised no one has ventured a guess about my lethargic
gouramis, particularly with no discernable other problems. So I am wondering
about doing not too invasive approach. I am considering more 30% water
changes and adding 1 TBS salt/ 5 gals. I also do not have an airstone in
this tank, so thought I might add one as well.

2 questions:
1) Is this a reasonable approach or is there something else that would be
non stressful to the 'well' fish.

2) In the tank I have 3 neons, 3 lemon tetras, 2 dwarf gouramis and a small
rubber lip pleco. Is salt determental to any of these fish, particularly the
pleco?

Thanxx
Bill Brister - Austin, Texas