Sorry; didn’t see the words.
follow the instructions on the bottle. Most coral dips won’t kill pests, but they will weaken them. And time is a bigger factor than strength; so go full recommended concentration but don’t leave the corals in it for too long. Also; most dips won’t kill eggs. So doing it twice with a couple days/weeks downtime is helpful to catch any newly hatched baby pests.
Nudies like to hide in cracks and on the underside of corals and plugs.
For example; I’ll put the corals in an appropriately strengthened mix of tank water and X drops of a given dip for about 5-7 minutes to weaken pests. After that, I use a pipette to gently blast the coral, being sure to get into all the cracks and anything that looks suspicious. Mosts pests won’t be able to hold on in their weakened state and will fly off. I will keep the frags in the dip for an additional 5-7 minutes as I blast away. Then promptly move them to a container of tank water for rinsing. I continue to blast and inspect in the rinse water during this time.
If nothing bad comes off during this, then they go to my QT system. After being in the QT for a couple weeks, if still healthy, I will do this again, transferring them to my main reef.
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That said, it could still just be stings from a neighboring coral putting out sweepers.
Could you do a closer or higher quality photo?