So, I have these flatworms...

[Triggreef]

And open top or not, I would still get a dusky. Worth the risk of jumping IMO. Can always put a top on it too.

 

[sbash]

Ok, so with that all said, I'd certainly hold off on further treatment until things recoup. I've used Flatworm exit on my system (back then was probably 260g or so). I had no issue with the treatment and good results. In my case it was red planaria, which I feel are tougher to eradicate than what you have. I dosed about 50 percent more than the directions. Reason being I captured some of the planaria and tested several different methods to kill them. The recommended dosage just seemed to knock them down for a few minutes and 10 minutes later they were slithering around in the container. But slightly higher dosage and it seemed to do the trick. In my case it was all out plague proportions. I used a 1/4 inch tube to vacuum out as many as possible prior to the treatment, and shortly after.

I had no issues with any tank inhabitants (mixed reef heavily stocked with frags and fish). I also repeated the process 5 or 6 days later to get any I missed. Don't forget nothing will kill their eggs.

I think @twilliard also devised a plan using peroxide for flatworms. Should be lots of threads regarding that. I believe it stuns them and sends them floating, where they can be filtered out via filter sock. and repeated several times.

Thanks! Yeah I'm definitely holding off, that said, it was a couple weeks ago now, so everything but the large fox colony is fully recovered (everything that survived that is...)...

I'm trying to figure out if it was my treatment or a contaminate in the other tank that caused the problem. There may be no way to know, unfortunately... Anyway, so it will be some time before I actually use the FWE, if I even do... I'd like to find something that will kill everything BUT the corals, then throw some fresh live rock in there and be done with the flatworms and any other hitchhikers, lol...

Also, it's a low boy, so a 2' by 4' top is a bit much, haha... Either way, I would rather not keep fish in this tank...