1) I have Durso on mine tank. Not really noisy at all. If you set it correctly it should be pretty quiet. Is it factory Durso or DIY?
In any case, try adjusting your return flow and it should reduce noise.
2) Not familiar with trigger sump. Is there a adjustable gate for each compartment? Also, since you don't have emergency drain, I'd not restrict the drain pipe. It should be fully open during operation. again, adjust the return pump flow to what you sump can handle.
Could be loose impeller or impeller shaft is broken?