Painted surfaces and glass. The biofilm on painted surfaces or glass is usually thin and easy to kill. Care should be taken to flood joint details, gaskets, edges and generally anywhere an alga could nest. Best results are achieved by using a water fed brush. The concentration can be adjusted to the amount of foaming desired. 1:40 gives a dense foam with good detergency. Rinse and leave to dry. Dry glass units from splashes of dilute.