Just wait for the 3-6 month period when diatoms, cyano, and hair algae are the plague in the tank. Tough part is the pollutants and phosphates have leeched in to the rocks and sand, and will not go away despite your every attempt! In my tap water starter tank I was gold for 3 months, then cyano, then hair algae. I tried EVERYTHING in the book on getting rid of it, but the tank was the problem. Cyano was only a 4-6 month battle, hait algae is still there a year later, but very slim, almost gone.
Good Luck! ( I would start diluting the TAP fast!)