I second Tom's post. It's ultimately just a money drain...you have to keep using it to "fix" (I use that term lightly) the problem, unless you actually fix the problem. You just have to keep tinkering.
Your plant load looks pretty low, also. You may want to stick in some fast growing stemplants to help outcompete the algae.
Your plant load looks pretty low, also. You may want to stick in some fast growing stemplants to help outcompete the algae.