Consequences of low return pump output?

[blaze422]

I have an external pump...Dolphin 3000 for my 180 and I realized the refilling hoses (from overflows to sump) have decreased flow. I broke down and replaced the pump and output might be increased 25-50%.(or I could be hallucinating)
Not sure how long this poor flow has been occuring...but I am wonderiing if you all think this could be primary cause of slime and hair algae I've been fighting?

 

[peterlin]

Same thing happened to me. The white rod of impellor of my Mag 18 pump broke. I don't know how long this has been but I lost 2-3 sps colonies. I probably would loose more corals if I did not have wavebox and tunze stream in the tank.