It could cause blindness in the eye one drop gets in, among the more caustic things we could own. if not blindness then however long it takes a cornea to unscramble then w be ok
Use safety spectacles
I recommend not experimenting with it in your reef to see how things work out, for that strength you should only use known safe application means where it was used and tracked for outcome vs random guessing on water doses, nearly everything you read online is designed for 3% use
I once messaged Randy in about 2011 to ask him if I had nerve damage from some that got on my palm and blanched it white lol (initiation rites for the +3% crew)
after your first skin contact, youll work to reduce that event. He was right no damage but learning from one shot did occur at the spinal-mediated level.