Grazer wanted

[blacknife]

my 50ish <36x18x20> is doing ok but i have a few old but healthy tufts of HA that are hard to pick out. I also have this parsley looking leafy algaee that covers one rock and is slowly appearing on other spots in the tank. I keep thinking about a small tang knowing that i might upgrade in the near future but what else could i put in there to clean up that parsley looking stuff?

<edit my small emerald eats the stuff but can't keep up with it but the big one won't touch it and neither does the LMB>

tank is mixed reef with sps starting to actualy grow good..