When to use? When fish show symptoms of a bacterial infection (ulcers, fin, tail or mouth rot, loose scales), parasitic infection (Costia, Trichodina, skin or gill flukes), flicking and rubbing against rough surfaces or gasping.   How to use?   Test your water quality using NT Labs Test Kits. Mix the appropriate dosage in a clean bucket of pond water and pour evenly over the surface of the pond. Switch off UV filtration until 48 hours after adding the final dose. Aerate the pond well during treatment. Add Filter Bugs 48 hours after adding the final dose to boost the biological filtration of your pond. If you feel a repeat dose is necessary, check your diagnosis using the Diagnosis Tool; a different medication may be more suitable. Allow 10 days after adding the final dose and perform a partial water change before re-treating or treating with a different medication. Always treat when you have time to observe fish and take appropriate action in the unlikely event of a bad reaction. Follow the safety information below throughout the course of treatment.