Could Flatworm Exit crash 2 tanks?


New member
On May 29 I treated my 125 for flatworms using Flatworm exit, I pulled my carbon and turned off the UV light. I followed the directions using half of the recommended dosage. One hour later I added 25% more not the 50% they recommend because not all of the flat worms were dead. I noticed my porcupine puffer lost his color, he was a pale color no longer yellow and brown, the copper banded looked fine at this time.

I did a 33 gal water change after waiting one hour, added the carbon and turned on the UV sterilizer.
I went to work
My wife called and said everything looked bad, I told her to mix up 20 gal of water so when I got home I could change it out.
When I got home the puffer looked as if it had a sun burn and was peeling, the copper banded looked fine.
I quarantined both fish in my qt tank, in the morning they were both DEAD.

On April 1 my friend Milt calls and tells me he has big problems with his tank, everything appears to be dying.
He had used the same bottle of flatworm exit on Saturday
only using half of the recommended dosage doing a 25% water change.
we quarantine all of his stuff and do another 25% water change. He looses 2 clowns and a Kenya tree that was 2-3 inches around and 15 inches tall.
He also lost a sea cucumber.
He did not have room for his 14 inch anemone and a percula clown, so I took them home and put them in my 125.
I checked all water parameters, everything was OK so I added the two. They are both doing fine in the 125
He put everything back in his tank 2 days later everything is OK.

What Happened???
What went wrong????

All of the saw blade caluper in my sump has died.
My tank looks fine everything growing like crazy.


I am going to buy 2 6 line wrasse
some black velvet nudibranch
any other suggestions would be appreciated.

I added the anemone and the clown to the 125 so now that all of the other fish are dead I will be turning this tank into a reef.
I have been pumping 1200 watts of light into it since day one, it has 150 plus pounds of LR and a mud refugium.

I just wanted to let everyone know what happened to me and my friend when we used flatworm exit. Be extremely careful!!


New member
You don't mention in your post, did you siphon off all the dead flatworms - I see you said you did a water change but don't mention sucking up the all the dead flatworms? I haven't used this stuff myself, but from what I've ever read on it you have to make sure and suck up all those dead flatworms otherwise they release toxins that can kill your stuff.

Link to something from melev on this topic:


In Memoriam
I have used Flatworm Exit with success. I followed all directions completely and exactly as indicated. This included siphoning all of the flatworms I could see prior to adding the chemical. I also siphoned off all of the dead ones I could see after the chemical was added. This is important because the dead flatworms can really mess up the water when they die if you have a lot of them.

Do you think you siphoned well? Adding fresh carbon back in may help if you have not already done this.

Something to consider:
Flatworms may be unsightly, but given time, they usually go away on their own, and they don't really bother anything. If you add other things to fix them, it can lead to new problems. For instance, velvet nudis can be very toxic. Adding two wrasses can clean your tank out of pods.


New member
I have used this product before and did not have any fish problems.
the saw blade caluper in the sump did die off before.
No I did not siphon out the dead ones
I left everything run all pumps and power heads
As they were dying I did not see them
I do not know what happened to the bodies
There were 1000 or more and they are back


In Memoriam
<a href=showthread.php?s=&postid=7563973#post7563973 target=_blank>Originally posted</a> by geppert
...No I did not siphon out the dead ones

That's why. There were probably lots of them dead behind and inside your rockwork. You couldn't see them to siphon them.

Miracle chemicals seldom work the way we want them to.

Sorry about your losses. Does not sound like it was your fault.