We've had one of these models in our waterfall for 4 years. It failed today after running almost continuously during that period. Our fountain is three tiered with a 4" fall spout. The top of the fountain is about 30" above the pump. The total volume of water in our fountain is less than 20 gallons. We're very pleased this pump lasted 4 years and will be purchasing this same unit as a replacement. The waterfall is outside and the sound of the pump is imperceptible. The small grill has kept out debris and we've only had to clear it once in four years - but our waterfall is in a rather clean area of the yard with no trees or other items that would clog the pump.