Hi Y'all, I know how to sanitize my fresh water system, but wondered what the products marketed as "water freshener" do? Are they intended to delay the buildup of algae? Do they sanitize the system too? Or are they snake oil? I looked at a bottle at Wally World, and was surprised to see all the warnings about it being hazardous to ingest, do not induce vomiting, call poison control, etc. I'm concerned about putting HazMat into my water system! What gives?