Unfortunately, algae is generally a fact of life in all tanks, and requires regular cleaning. The easiest way I have found to clean glass is to use a high quality magnetic glass scraper. I really like the Algae Free magnet cleaners:
Algae Free Algae Magnets
They are more than the cheapo plastic ones you can get at any LFS
, but they are worth it. The cleaning pads are far more effective and the magnets are far more powerful.
You can help reduce and control algae, but it is nearly impossible to eliminate it, and glass will require regular cleaning. For reduction, we can talk about a few things:
Are you using RODI
What are your water parameters in terms of NO3
What kind of lighting do you have, and how long per day do you light the tank?
How much do you feed, and what is your stock? Also, what do you feed?
Does the tank get any natural sunlight?