First, let's talk lighting. Set it for 8 hours. Only blues and violets. No reds, greens, or whites of any kind.
Second, while I understand it isn't cheap, get the UV. Not just for this algae, but having one is going to reduce disease in your tank by a lot. Fighting disease is often very expensive and stressful and can take a very long time. Don't do this to yourself or your fish. Once you get one, you want the flow into it to be very slow. Not so slow that it isn't constantly filled with water, but the longer the water is exposed to the UV the more effective it is at killing the bad stuff. Too much flow means it may hardly work at all.