No chemicals must be used to clean the docks, if chemicals are needed you must have the docks removed. When sealing only water base products must be used. When treating them use a painters pad when apply wood preserative, and have someone in the water catching runoff with a tarp or cardboard. When I do docks I contact the DNR and tell them what and how I am doing it, and ask for a letter saying it is oky for me to do this way. So if another DNR person comes up to me I show them the letter and everthing is cool. Lastly use cold water to clean. Good Luck
Charlie