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.
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.
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.
After an hour or so you can turn any UV or ozone on again.