Don’t panic. Flatworms can come and go without chemical intervention. I would say if you can’t really see large numbers of them, you don’t really have an issue at the moment. Besides that, even if you use Flatworm Exit, you still have to siphon out as many as you can before treating the tank. You see, the flatworms are probably more of an issue when they are dead inside your tank. They can release toxins, which is why you want to limit the number of dead ones and why you need to run carbon - after you treat with FE.
Some wrasses will eat flatworms, so I would try a natural approach first. In any event, I would siphon out the ones you can see and keep a close eye on their numbers. I am beginning to have some serious doubts about your LFS.
Become more independent. Set up an RO/DI and get some large containers to store fresh and salt water to use when you need it. That way you will know exactly what you are adding to your tank and nit rely on whatever you can round up at the LFS. My two cents - again.
Some wrasses will eat flatworms, so I would try a natural approach first. In any event, I would siphon out the ones you can see and keep a close eye on their numbers. I am beginning to have some serious doubts about your LFS.
Become more independent. Set up an RO/DI and get some large containers to store fresh and salt water to use when you need it. That way you will know exactly what you are adding to your tank and nit rely on whatever you can round up at the LFS. My two cents - again.