Well if you see hundreds then there is probably thousands of then is all of your live stoke there and can you acount for every one you know of if there is a dead solder in the tank it could cause an increas in the flatworms in your tank. You see decaying food sorces are there friend they thrive when people over feed the tank or things start dying and are not removed. Or the other thing that can make them multiply fast is water peramiters are out of wack and you are testing for the right thing to let you know what caused the boom in flatworms. If your wrasse can ot keep up with there populations and you want to use flatworm exit or some thing else I would sugest you remove your fish and inverts before hand. Flatworms excreet a toxin when they die and you could loos some or all of your live stoke if you can't keep up with the siphoning and water changes that are needed to over come the flatworm toxin. If you remove your fish and inverts it will give you some time to keep up with the siphoning and water changes, you will not have to keep itup if you get realy tired. You can have a nap and resume when you get up again.
I would say better to be prepared than not.

Bill