Try flourish Excel. Its more money than DIY CO2, but easier and if carbon is the one thing limiting the plants growth, it should help the plants outgrow the algae. There are definitely "algaes" that plecos won't touch so you may need to feed sinking wafers for the pleco to eat. Both more water changes (to reduce nitrate) and less light should slow the algae's growth, but also the plants' growth.
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