I've had the weirdest issues with my pool build.
The pool has a waterfall. Based on a waterfall at a house we rented, I figured I needed 80-100 gpm to make it look nice.
When I developed the specification, I had a 2" pipe to and from the waterfall and a 2-way valve to adjust flow.
Waterfall is about 40 feet from equipment pad and about 6 feet of rise above it. Probably, 5-7 90 degree elbows between pump and waterfall.
I allowed the pool builder to pick the pump.
The PB decided on his own to make the piping 3"....and he wanted to use a 2 HP WhisperFloFX.
I told him I didn't need/want that much flow.
So I agreed to a 2HP WhisperFlo WF-8.
I figured I would use the 2-way valve to restrict as necessary.
We don't run the waterfall all the time...so no big deal as far as energy consumption, etc.
The very first time the pump was turned on it made a screaching sound.
PB contacted Pentair rep and this was the response:
Sounds like it is what we call "freewheeling" or at the far end of the pump curve.
Pentair suggested restricting the flow with the 2-way valve. I tried that and the pump became quite.
The valve is a FullFloFX valve. If 9 o'clock is open....I have to turn the valve to about 10:30 or 10:45 before the pump gets quite.
The problem is that the valve makes about as much noise as the pump when I restrict the flow.
Once I get to 11 o'clock all is quite, but the flow at the waterfall is not enough.
PB also suggested piling rocks on top of 3" opening in waterfall basin to help restrict flow. I tried that...helps a little. If I seal up the pipe to much....Old Faithful for a while....until the rocks are moved by the water pressure. I'm talking 20 pound rocks!!!
I first thought...get a smaller pump.
When I look at the pump curves, all the pumps "max out" above 20 feet of head.
I'm not sure that I've got 20 feet of head since the PB used 3" pipe.
Thus, I'm afraid a smaller pump will simply pump less but be just as noisy because it is at the far end of its pump curve.
FINALLY MY QUESTION:
How can I quietly introduce a sufficient amount of head so that my waterfall pump is not at the far end of the pump curve?
I've read a lot of posts trying to reduce head....this might be the first one trying to increase head.
Thanks for your help TFP!!!