flat worm exit worked very well on my 34 gl tank.
I now have a 120..if I had flatworms, I think I would use a fish/nudibranch to remove b/c of the required size of water change need when killing off that many flatworms. Flat worms are only bad b/c they can grow to outrageous numbers and smother corals...other than that they are ok. So if you have a fish/nudi to keep the FW population in check, it should be ok(of course if you give them to someone else, they will be mad, ie rbtwo4)
If you do use SFWE, Dace is right, siphon out as many as possible as they release a toxin when they die, if the FW pop. is large enough it will over power your system and kill livestock. HOWEVER, depending on you tank size, 25 gallons might not be enough.
Good luck
PS Ive had alot of fun in Huntington at the bars on that strip(when I was younger), fun area