Filter for Overstocked 10 gallon

I will look into teh Hydo Sponge idea but I'm not sure how much better it would be?

Would I be ALOT better off with an internal Fluval? The HOB idea is most attractive, what if I modified the outlet to have less surface agitation? Since the tank will sometimes be overcrowded, maybe a little more than optimal surface agitation will be beneficial.
 
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