Jpap and Dundadun's got it. Find the cause, and not add a species to "fix" a problem. Not all algae-type eatters, eat all types of algae.
While I agree with this in general, I dont see a problem with diversifying your microenvironment to balance the system so long as you have researched that the addition wont cause another problem and you can keep up with the added bioload. Algae eaters exist in nature and do their jobs well, I'm all for taking advantage of that, within reason.