way to kill red flatworms

So I've had hell with some red flat worms in my tank. I've battled them by water changes and sucking them out, dropping my feeding and trying to starve them out, blacking my lights out as long as I can, and using meds. All with no success. The other day I accidentally left my heater off in one of my tanks and then noticed that the worms where almost all gone. I thought about it and realized that all the tanks I've had in the past that had some heat difficulty (ran a little high at 80) the worms thrived in and all the tanks I've ran a little cold they have not. I'm not sure if I will be able to 100% kill them with a temp drop, but I don't see any in the first tank that I did this in and have the best response of any treatment in my second tank. I have not read anything about this. I'm not the best at research, but I sure wish I knew this some time ago, so I thought I'd post it up here and see what people think.

 

it's been a little bit of a give and take because I don't want to drop my temp to much for to long because I have some coral left in this tank (most coral has been dipped in a iodine bath and moved), but it's slowly working. They seem to start shriveling up or at least not flatting out fully when the temp is around 70F or below.