Variable Speed Waterfall Pump?

[Rwmiller80]

We have a 1 year old pool built with TSP support and managed the TSP way. All is good with the pool and we can’t wait for the weather to warm up. It has a 6 foot wide 18 “ high waterfall feature powered by a MaxFlo XL pump with an output valve to throttle flow. It works great but runs louder than we would like. Depending where you are, you hear the pump more than the waterfall. I have been thinking about replacing the pump with a MaxFlo VS pump as I know how quiet our Variable Speed filter pump runs. But I am worried that I would need to run them waterfall pump at such a high speed to get the flow we want that it wouldn’t be quiet. I have tried doing pump head calculations but not sure what I am doing and I don’t want to make an expensive mistake. We tried a sound deadening cover on the pump but not much help. Thanks for your advice.
Bob

 

[mas985]

The MaxFlo is not really a waterfall pump. In fact, it is really an AG pump. Kind of an odd choice for a waterfall. A couple of questions:

Do you usually change the throttle settings on the pump or is it normally just fixed to one position? If the later, then the VS might be overkill. There are other things that you could do such as downsize the impeller to avoid throttling but then the pump will have a lower maximum flow rate.

Why are you throttling the flow rate? Is the waterfall too active or is it something else?

How much is the valve shut down? (pic might help)

If you fully open the throttling valve, does the sound get louder or softer?

What is the HP rating for the pump?

What size pipe is used for the waterfall?

 

[Rwmiller80]

Thanks for the quick reply. I have added my answers next to each of your questions.

Do you usually change the throttle settings on the pump or is it normally just fixed to one position? If the later, then the VS might be overkill. There are other things that you could do such as downsize the impeller to avoid throttling but then the pump will have a lower maximum flow rate.- we don’t normally change it. Just leave the valve in one position which is why we originally didn’t get the VS pump. Didn’t realize how loud this pump would be. We like the idea of using a pump that matches directly up with the existing piping to minimize work. Our pad is very compact.

Why are you throttling the flow rate? Is the waterfall too active or is it something else? - we like it to fall less aggressively than it does when wide open.

How much is the valve shut down? (pic might help) - we are running about half way open.

If you fully open the throttling valve, does the sound get louder or softer? - The pump noise gets a bit quieter but the valve is noisier due to flow noise. The pump noise is what is bothersome.

What is the HP rating for the pump? - 2.5

What size pipe is used for the waterfall? - 2 inches it’s about 50 feet from the pump to the waterfall.

Thanks again,
Bob

 

[mas985]

You basically have two choices.

1) A VS will allow to fine tune the flow rate but costs a lot more and as you mentioned, may not yield much in energy savings.

2) Downsize the impeller. Harder to do and requires a pressure/suction measurements at the pump drain plugs.