I had the same problem when switching tanks
I put all my rock in 5 gallon bucket
Along with the SW from the old tank
I then put FW exit in each bucket and let it sit well beyond the time recommend
I didn't want any of them showing back up
I even did a fresh water dip for a few seconds with everything just to make sure
Fresh water kills them instantly
I used all new sand none of the old FW infested sand
I also did this with all of my corals cause they will be on there also
FW exit causes all the FW to die but when they die they release a toxin
But doing it in buckets and not reusing that water I wasn't worried about the toxins
My new tank has been up for a few months and no signs of any FW yet(knock on wood)