Macro-algae eaters??

[Mark75]

As my tank gets older I am having a problem with macro-algae. I am running GFO and using RO/DI water with a reading of 3 TDS. At first the small patches of algae were no problem but without and predadation they are quickly becoming an eye sore. I try to manually remove what I can but some of it is impossible to reach. I need biological help! Can you recommend any macro-algae eaters for a 30 gallon tank? I prefer fish as I have several types of snails and hermits and they do nothing as far as controlling the macro.