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Salifert Flatworm Exit


Item #: SF5111

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Flatworm eXit itself is quite safe to fish and invertebrates. However, the body juice of flatworms can be toxic to some reef inhabitants when present in a too high concentration. This body juice is sometimes excreted when flatworms die.

So when you use this product it is important to do the following first:
  • Siphon out as many flatworms as possible.
  • Keep sufficient fresh activated carbon in a canister ready.
  • Turn off UV, ozone and remove activated carbon. Keep the skimmer turned on.
Important remarks

Below given remarks are a.o. meant to reduce the amount of the flatworm`s toxic body juices in the water.

Many people have treated their reef tank(s) successfully using Flatworm eXit without any problems. The most important factors are reducing the number of flatworms before commencing with the treatment and reducing the amount of the flatworm`s body juice, released when they die, as fast as possible.

Do not underestimate the number of flatworms in your system. In a few cases a significant number of flatworms can be hiding in, for example, crevices. Blow in such and any other potential hiding places, water, to blow any flatworm out of there. For that purpose you can use a powerhead or a turkey baster. Siphon out those flatworms as well.

Furthermore, do not underestimate the amount of toxic body-juices these flatworms can excrete. This can be reduced significantly by really siphoning out the flatworms before commencing with the treatment. Further significant reduction is accomplished by siphoning out as many dead flatworms as you can.

Any body juice released by the dead flatworms in the water has to be reduced further by using about 1 pound of fresh high quality carbon for every 50 gallons. The carbon has to be used in a canister with a sufficient forced water flow.

Take sufficient time for treating the tank. That is, do not treat your tank in a hurry. Also, take time to monitor your tank for at least 6 hours after the treatment.

It is also wise to have at least 25% water ready for a water change if required.


Read all the above text before commencing with the treatment!
  • 1 drop for every 4 liters or 1 gallon
    The dropper contains approx. 300 drops (10ml). The dropper cap holds approx. 90 drops. So 1 cap full is good for 360 liters or 90 gallons.

    Add it in a high flow area of the tank. If you want to treat a refugium only and if it`s volume is too small for using a powerhead then mixing should be done manually.
  • It should start to work within 30 minutes.
  • If within 45 minutes no visible death of flatworms occurs add 50% more.
  • As soon as the flatworms start to die, commence with the activated carbon to take out any toxic body juices. Also see the above given important remarks.
  • After an hour or so you can turn any UV or ozone on again.
Keep out of the reach of children! Only for aquarium hobby use.

Manufacturer information

Salifert is a Holland base company that produces top of the line test kits as well as tank additives and foods for marine and reef aquariums.

4 Stars


Reviewed on
May 12, 2020

Yes, I would recommend this.


Pros: It works

Cons: Not sure

Awesome I used the full bottle and a 30% water change and a week later no flatworms.

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Reviewed on
October 31, 2019

Yes, I would recommend this.

FWE Works Great!

Works really well, follow the directions, multiple treatments may be needed.

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Reviewed on
July 24, 2019

Yes, I would recommend this.


Pros: It killed some flatworms and my livestock was uneffected

Cons: It did not kill all of the flatworms.

So I got this product thinking it was gonna fix my flatworm problem.... It helped some. I have only dosed once and followed the directions to a T. The first time around it killed some flatworms but after 24 hours I still have flatworms. This did not kill as many as I thought it would. I am going to dose again soon. On the plus side it did not harm any of my livestock. No corals, fish, or crabs died or seem to be harmed.

Was this review helpful? 1 0

brian palmer

Reviewed on
October 31, 2014

No, I would not recommend this.

Does not kill eggs!

I'm getting ready to try this product again. I believe it can work but there are some things you need to keep in mind before you start. One of which is although this product does kill the worms they almost always come back. It does not kill the eggs. I did a series of five treatments over 6 weeks. After the last treatment I did not see any worms. A few months later I notice they are back strong as ever. I'm skeptical of some other positive reviews. Could be they came back for them as well. For a big tank this get expensive really fast. Hundreds of dollars. Salt , carbon and FWE. It is believed the AEFW life cycle is about six weeks so maybe Red Planaria is about the same so... My plan is to do treatment for two months and see what happens. Have some extra FWE on hand to do periodic treatments afterwards to check. But don't go long enough they could mature to sexual maturity. It is believed this product does not kill eggs so they hatch after you've done treatment. The key is to keep doing treatments and try to kill all babies before they can mature to produce more eggs. Toward the end of my 6 week treatment I did not see any dead bodies ... don't get sucked into believing they are gone. Also if you don't have a brine shrimp net get one before starting. When the treatment starts to work the bodies will be floating all around the tank. I sit there with my arm in the tank and net out bodies for 2-3 hours. I replace my fuzzy fiilter socks with mesh filter socks so they can be cleaned out easier and quickly. You do not want the worms to sit in those filter socks very long. The bodies literally start to melt within an hour or two. If you put the dead bodies in a bowl and watch you will notice the bodies just start to melt into a nasty orange poison. So it's very important to get those bodies out. Keep pump running so the treatment gets all areas of the system. (except carbon reactor of course) I give this product low marks because I believe the maker could divulge this information but chooses not too. Hopefully they will let me edit this review in the future. I will report back in a few months.

Was this review helpful? 9 0

thomas amick

Reviewed on
May 29, 2013

Yes, I would recommend this.

flat worm exit works. almost

Killed almost all flat worm and followed directions. Wrasse wasnt eating anything. A few still survive so I'll use again in a week and see. Maybe they a like ich that cat be killed in certain stages of life. It kills worm instantly and just follow directions. All livestock corals and amphipods still alive abd didnt even notice. The water change and vacuuming was more stressful!

Was this review helpful? 3 0

justin salvato

Reviewed on
August 08, 2012

Yes, I would recommend this.


OK, We ordered this to deal with a few flatworms in my 90 before they became a problem. I also was fighting zoanthid eating nudibranches in my nano for some time, losing frag after frag of really hot zoanthids, I was ready to give up. While researching I came across someone stating that this product was highly toxic to nudibranches, so I decided to give it a try. Dosed the 90 and saw about 5-10 flatworms floating dead in the tank. Dosed the nano, and sure enough, caught a view of a nudibranch withering up and dying. I took such joy in it. We dosed my brothers two frag tanks, a 70 and a 20 where we had previously spotted a few nudis. My brother was actually able to pick one off, put it in a 1 drop to 1 gallon mix of flatworm exit, and sure enough, dead nudi. We have suffered NO ill effects. All tank critters seem unaffected and healthy, even my fan worms and feather duster are ok. No effect on copepods or mysis as others have suggested. Salifert really needs to market this as nudibranch erradication as well. Very happy with the product. More than a week later, I have zoanthid colonies bouncing back that looked dead and gone previously. To the mad scientists at Salifert, we salute you.

Was this review helpful? 9 0

jerry search

Reviewed on
February 05, 2012

No, I would not recommend this.

Does not work.

I'm sorry, but this stuff did NOT work. I have a 40 gallon refugium infested with flatworms. I tried Flatworm Exit 6 months ago, but I think I accidentally re-infected the aquarium. So this time I tried a new bottle. After the recommended dosage, many flatworms did die, but not all of them. After removing the remaining chemical, and the toxins that would have been released, I noticed that there were still many, dozens in fact. This time I used a triple dose, almost the whole bottle. After about 8 hours, the little buggers are still there. So now I will resort to drastic measures...

Was this review helpful? 0 3

joel clark

Reviewed on
November 27, 2011

Yes, I would recommend this.

Great, but follow instructions

This product does a number on flatworms, but you must siphon out as many FW as you can, filter with carbon after use and do a large water change. You need to follow up in about 5-7 days with another treatment to get all the eggs that are not affected with the first treatment. If you follow directions and treat at least twice, it should do the trick.

Was this review helpful? 6 0

mark s acker

Reviewed on
November 25, 2011

Yes, I would recommend this.

There is nothing else

I have used several products in the past to treat flatworms, but this is the best by a mile. One treatment in a 210G and the worms were gone. Unlike other products, I did not have to up the dosage, nor did I have to re-treat. One and done! My mushrooms are extremely happy now! I love it when I can find one product that I know is going to work for whatever the situation it. For flatworms, this is IT!

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nathan laidlaw

Reviewed on
November 21, 2011

Yes, I would recommend this.

Great Stuff!

Worked great, easy instructions. A capfull to my 72 gal system functioned like a charm, killed my acro eating flatworms and a few red/brown planaria I did not know I had. No adverse side effects (very few flatworms vs tank volume). Did not erradicate all flatworms (99% gone), will have to treat a second time (and to catch any new hatchings of egg sacks). This was expected, have used product in past and needed to treat twice then as well. Follow all instructions--if you do not siphon out all flatworms you can get to, it can crash your tank when they die and spew toxins into the water.

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