Algae needs 3 things to grow: nutrients (usually increased nitrates or phosphates from overfeeding), water, and light - usually cutting down on the nutrients (feeding) and keeping up with weekly 1/4 water changes will keep algae to a minimum. If nitrates are high I would suggest 1/4 water changes every 24 - 48 hours to reduce levels more quickly. If you have a fish only set up you can also decrease the lighting time to help starve out the algae. Clean up crew snails, hermits, etc. will help, but they won't be able to stay ahead of it if nitrates are high. Also, make sure replacement water is nitrate free.