Flat worm complete die off

[pastout]

ok so i am trying to revivie my fiances 10 gallon nano i built her and picked it up from her parents house and it had a complete infestation of flat worms rocks were completly red the grvel was all red witht hem and the glass was covered with them did a couple water changes because the salt level was at like 1.032 so ive been workign on bringing it down have it down to about 1.027 now and put two new lights on it two power compacts and when i looked at the tank today all the flat worms have curled up and died i cant find even one left. any idea what might have caused this? not that im complaining

[JDigital]

Possibly the rapid change in salinity?