Mixtures that use photoactive agents that inhibit the growth of algae are disclosed. The agents include concentrations of approximately at least 5% to approximately 50% TiO2, WO3, PtWO3-Pt-WO3, or Pt-TiO2. The agents can be combined together, and/or each agent can be combined with various coatings such as but not limited to a cement or a polymer binder. The coatings and agents can be applyed to surfaces that are exposed to water such as but not limited to an aquarium, liners on the inner walls of swimming pools, drinking water tanks and the like. Further, applications can include using the novel surfacing agent as part of a solar water heater for both a home and a pool, wherein in the latter application the heater is connected between pool pumps and the pool so that when light is absorbed inside the heater, the surfacing agent becomes active for inhibiting the growth of algae. The photoactive agent can also be applied as a non-toxic algae-retardant marine paint.
