Algae will never go away, nor do you want it to. Since you say your tank is cycling, I am assuming that your frustration is with brown or tan colored algae? If that is the case, then what you have is diatoms, the topic of much discussion on this BB. Diatoms are heavily present in new tanks because new tanks have a heavy load of silica in it, silica being a food source for diatoms. Once the diatoms eats up the silica they will die down and be replaced by the more desirable green algae. Phosphates is also a food source for diatoms, which is present in water as well as most sea salts. Test your water source and sea salt and go with a water source that has no phosphates and a sea salt that has min. or no phosphates.