Kiki's problem was free floating algae blooming in the water turning the water green. The algae that grows on the glass like a film is normal when there is a lot of light (even indirect sunlight from a window). You can get cleaning magnets or scrapers that do a good job of cleaning glass. It doesn't take much nutrients for that kind of algae to grow, but decreasing the light that hits the glass will help reduce it a lot.
Partial water changes are good for general maintenance and cleanings. But if your trying to combat a big algae problem, you will need to do larger water changes, like 85% to 100%. If you have a lot of rocks where waste could be accumulating, you will need to vacuum that out too.
