yes coil cleaner is a mild acid, I run a service department for a large mechanical contractor and have both hvac and plumbers working for me. The urinal stuff is bad too lol we use it often. Years ago I bought actual pontoon cleaner for a project I was working on and that was super expensive…I just have this stuff laying around lol, you just have to neutralize it before it starts to oxidize. I have always had boats but none that the prop really mattered on lol, just small river boats and John boats. I bought one this one for my dad, he always wanted one and he had to have open heart surgery so I rushed to get it water ready so I could take him out before his surgery so he would have something to look forward to and keep his hopes up in the hospital. Now I’m trying to get it actually reliable before he gets out lol….i live in Houston,TX and we are already having 85* days lol.