It sounds to me that maybe you've got too many phosphates in the water. I've noticed that whenever any algae shows up in my tank, it's because of the phosphate. Maybe lower your phosphate dosing and see if that helps. Maybe you don't need to add it 3 times a week, only once. It also sounds like your water change may be a little high. How many gallons/litres is your tank?(please mention dimensions too)

50 gallon freshwater tank, HOT Magnum filter (used for Mechanical Filtration only, 2 T5 bulbs equalling 17500K @78W. No Co2 injection. No Chemical Filtration.
1 brushnose pleco
6 Peacock Gudgeons
4 Green Flame Tetras
6 Serpae Tetras
2 Kuhli Loaches
2-3 Amano Shrimp
Red & Green Tiger Lotus, Amazon Sword, Water Sprite, and Broad Leafed Red Ludwigia