Butterfly gives really good advice, don't use medications in your tank. Algae is really NOT
THAT bad of a problem, it is unsightly, but nothing to medicate over because it can be taken care of with normal methods.
#1 Light - wrap the tank as suggested. Then on a regular basis only light 5 hours at a time. UP to 10 hours a day with 2 hours off in the middle. You have to do several water changes and gravel vacuums after a dark out period as suggested. The reason for this is that there will be a algae die-off, and if you don't get rid of the dead algae, it will feed the next wave of algae growth!
#2 - What is meant by heavy waste, is that EITHER your nitrates are high - over 20, in which case you need to up your water changes.
OR you need to be doing a better job of vacuuming your gravel with your water changes.
What is your nitrate reading? How much water do you change out every week?
Do you have an algae eater of any kind? I'll check your signature, but have you told us about your tank and what you currently have in it?
After we find out about your tank, there may be some more recommendations.