Huge flat worm issue

[freeze]

There is nothing wrong with flatworm exit, the problem is that when they die, the release poison, which you know. I spend a week syphoning out all the worms I can see into a bucked running the airline tube into a filter sock then return water and keep going. Once you have 70-80 % out you will minimize the toxin released.

Once you add the meds, then suck out all that you can see.

Run carbon and then do 25% water change and then another 20-25% the next day.

In the boat your in, change water, lots of water and carbon. You might also want to remove anything alive and quarantine them. then treat your tank like crazy and then do lots of carbon and massive water changes.