consequences of overskimming?

[vanreefer]

I curreently have a 77 G mixed reef with a moderate bioload. I am setting up a sump and NEED to replace my Cough seaclone Cough. I plan to set up a 200-250 gal reef within the next 2 years and I want to buy a skimmer that will be able to handle the larger system now. My question is what problems, if any, will I have in my 77? I am looking at the ASM G4 mmmmmmmm big skimmer
Thanks,
Dano