ahh now were talking keeping water not fish. well if its non planted its 1000% easy, cut your lighting to just when you look at your fish and do more waterchanges this will remove excess nitrate and phosphate, also dont overfeed.
with planted this is a whole new ball park and will require testkits for phosphate,nitate plus premixing your water and getting a fert dosing plan to suite your lighting photoperiod. sounds technical becouse it is and may take alot of trial and error at first to get your tank optimal and algae free but when you get there its a real achievment. some say hightech planted is harder than keeping reef becouse you need microtraces of nitrate and phosphate not nill like marine