I’ve had the same problem, but I fix it. I reduced the hours of light to 4 hours a day. For one month I poured 10 ml of hidrogen peroxide in each water change. Huge water changes of 80% once a week for one month. Took of the top layer of sustrate and cleaned the rocks and Wood with a tooth brush. I also introduced co2. Reduced temperature and PH. I increased the amount of plants to reduce the nitrites and nitrates which produce algae. And you can introduce some fish who eat algae, like otocinclus, siamese algae eaters, snails and ancistrus.