It won't really help that much. Skimmers are effective in SW setups because the SW allows for the creation of much smaller bubbles, which churns the protiens out and into the dry foam. In FW, it will cost much more to get the same size bubbles. If a tank is really overstocked--to the point where just the agitation from a HOB return is creating surface bubbles--it will help a bit, but in this case, reducing stock or increasing water changes will be a better solution. IMO, don't waste your money for a FW tank.