Copper is pretty harsh on fish even with scales, so it's often times deadly on scaleless fish and invertebrates. I wouldn't.
I've used it before on plecos but only a half dose, and you won't get rid of the tank snails like that. Just disinfect the fish.
Best bet is to take the pleco out and give him a dip to remove any snail eggs he might be carrying. Then put him in a clean tank and keep him there until you are certain he is not a carrier. I don't know if snail eggs can go through the pleco digestive system alive, but I wouldn't doubt it.
Then disinfect that snail tank with a blowtorch and gasoline
( kidding...kidding... I'm just kidding!)
I like to use water and washing soda (sodium carbonate) which will disinfect the tank. Don't just wash it but let it soak for a while. If you leave it longer it kills more germs.
I think it is gentler on the silicone rubber and acrylic Plastics than common sodium hypochlorite bleach, but most people use bleach because few people buy Washing Soda any more.
Ising copper will kill any inverts you later add. If you have an outbreak of snails check your feeding and tank maintenance
You have to get the copper back out of the tank by doing water changes and using carbon. A copper test kit from API will tell you where you stand.