OK.I have sand as a substrate, 28G Tank, 1T9 light and it is on for eight hours a day, no CO2 yet but on friday yes, temperature 25.5'C, pH 7.6, nitrate level (don't know how accurate [API] ) ish'' 1-2ppm. The algae has been sorted, I have blacked out my tank for 4 days and it has gone :)...