I want to come back to an earlier point first, before turning to the last posts, and this has to do with so-called "algae-free" planted tanks. These do not exist; there is always going to be some species of algae in an aquarium. The aim is to keep it under control, and that is possible. Plants will "out-compete" algae but the light and nutrients must be in balance.
Floating plants will help, but in my view you are going to have to lessen the light intensity to really get at this brush algae. You are not over-fertilizing from what you have told us, and that can cause this too. The duration of the light is important, but duration and intensity are not interchangeable, meaning you cannot make up for one with more or less of the other. You are at 7 hours, and I would not go below 6, but that is in my opinion really not going to do much.
To illustrate how delicate this light issue really is: I brought brush algae under control when i reduced the duration of light down to 8 hours. I have moderate light, some say it is low light, over my tanks to start with, but brush algae was a problem until I reduced the duration to 8 hours. Over a period of two years I noticed that the brush algae also increased during the summer, and I came to realize it was because of the increased daylight during the longer days. I added heavy drapes and kept them closed during the next summer, and with no other changes, end of brush algae problems. This has now worked the last 2 summers. It was simply the increased ambient room light from the brighter sun during the longer days that affected the balance.
I would increase your water change volume to half the tank, and stay with once a week.
The wood in my tanks is absolutely covered in brush algae. I don't worry about it. I take action when it begins to increase onto the plant leaves. And there are several types of "brush" algae, as the attached photos show. I have both of these, though not in all tanks. It is another aspect of a tank's biology being unique that certain tanks will attract one algae but no others.
brush algae1.jpgbrush algae2.jpg
Byron Hosking, BMus, MA
Vancouver, BC, Canada
Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]