Fine Tuning Flow Adjustment When the flow adjuster on the Adaption Tee is set, so that the waterfall W is under the arrow, the output of the pump is restricted to provide a good flow to the cleaning rotor (to make sure the filter does not block in very dirty conditions). In many situations this provides more filter cleaning than is necessary. This is the case where a pond is not very dirty or the pump is already restricted by pumping up to a waterfall, external pond filter, etc. See Troubleshooting, "Excessive reduction in pump output" section.