Algae is a natural part of any aquarium ecosystem and will never be completely eliminated. The key is balance. Green spot algae (hard green dots on glass) indicates low phosphate or too much light. Green water (cloudy green) indicates excess nutrients with high light. Brown algae (diatoms) is common in new tanks and disappears as silicates are consumed. Hair algae indicates excess light and nutrients. Black beard algae (BBA) indicates CO2 fluctuation in planted tanks. Address root causes: reduce photoperiod, reduce nutrients through more frequent water changes, increase plant biomass, and use algae-eating species. Related fish: Siamese Algae Eater, Otocinclus Catfish, Bristlenose Pleco. Related plants: Java Moss, Hornwort (outcompetes algae for nutrients).
