Alkaline in-use solutions that may be used to disinfect and/or sanitize hard surfaces and which may act as anti-biofilm agents, comprise a disinfectant/sanitizer cleaner solution and an activator solution that are mixed together to form the alkaline in-use solutions. Disinfectant/sanitizer cleaner solution may comprise quaternary ammonium compound and hydrogen peroxide. Activator solution may comprise alkaline buffering agent, chelating agent and soluble silicon dioxide.