First find the source of excess nitrates and phosphate so once the algae is gone it won't come back. Most likely from food or water. Thaw and rinse frozen food and best to avoid flake as it is high in phosphate. Good quality top off water and for mixing salt is also important so a good ro/di unit is a must. Kalkwasser will help precipitate phosphates, along with a good skimmer set to skim wet. There are many
phosphate remover products available but be sure to research before using. Most work too good and remove phosphate quickly which can cause issues with livestock if done too suddenly. Nitrates the best way to reduce is no wet/dry filtration, good wet skimmer, and deep sandbeds 3"+ will provide anerobic zones that bacteria will use nitrate as food. Also refugiums with lots of macro algae will help and makes a good export.
Mexican turbos are probably your best algae eating snails. There is also a Bali monster that is an algae eatting machine, trouble is once not any algae anymore they usually starve.
Save your money on any hermit crabs they really don't do much.
Emerald crabs to a pretty good job on bubble alage if only a little bit present they can usually keep up. If tank is overrun then manual extraction is about the only good option.
As far as fish, Rabbitfish are probably the better of the
algae eaters better than most tangs but they can get large and will need a good sized tank or trade back in at fish store once they reach an appreicatable size.
