LEE COUNTY, Fla. — Wednesday is the last day in the two week trial for Lake Guard Oxy, which is an algae killing power. South Florida Water Management officials had been testing the powder’s effectiveness near the Franklin locks. The water district said that the powder is doing it’s job and that they just bought more Oxy for future use. NBC2 is working to find out more on when and where SFWM crews will use the Lake Guard Oxy. HOW LAKE GUARD OXY WORKS: