wait. poly filters remove phosphates and are condition indicators? is that poly as in poly(ester?) fiber that you get anywhere (LFS, craft section, etc)? or poly filter as in the one they are trying to sell with that link?
Anthony nailed the answer. Check you micro and macro nutrients and CO2. When your plants have those parameters you will get an oxygen saturation condition during photosynthesis. This is when the algae is really beaten. Tom Barr (AKA plantbrain) can explain it better. Search for some of his past articles on the subject.
I would try to add some plants that can utilize a bicarbonate source for carbon such as Vallisneria or egeria densa. The idea is to use plants that can outcompete the algae your java ferns and banana plant grow relatively slow. Since you added fertilizer to the system I would think that you have fairly high phosphate levels, and this is the nutrient that is often limiting plant and algae growth. By changing water so often you are also adding more nutrients to your water. The best way to beat algae is usually to let the right plants in high enough numbers outcompete. Plants that grow out of the tank or on the surface,ie..water lettuce, duckweed, are also great for beating algae.
Hello, I am new here and I don't know a whole lot about all of the specs... but I do know what has worked for me personally.I used to have an issue with algea as well. It would grow on the glass like crazy, no direct sunlight and the lights stayed on only long enough for my little girl to watch the fish in the evenings and at night while she went to sleep. I tried different algea eating fish and they helped but after a while they sorta just stopped eating the algea. So I decided to do a little research and seen something somewhere about pond snails. I went to the local park and got about 10-15 pond snails took them home and floated them for about 1/2 an hour and popped them into the tank. (which was at the time looking alot like the tank in Finding Nemo during the planned escape) Within 2 days my tank was totally clean! I have found that the snails get no bigger than about the size of a small pea and are bearly noticable. They have yet to over populate my tank and from what I have been told... they will only reproduce if there is adequate food supply. (not too sure about that one) I do know that since I have put them in my tank... I have not had a hint of algea in my tank. Between my live plants and my pond snails... my tank stay nice, bright and clear. Hope this helps some.