Can a Pool Pump Be Too Powerful? 

Safety first always, but I have frequently run into another related issue...cavitation. That's where the suction plumbing is insufficient to supply the pump with the amount of water it needs to operate properly. You can hear a pump cavitating because it runs louder than it should, has a distinct sound. One example is a pool had a 12 foot sheer descent on the back wall. Each foot requires at least 10 gpm to get the proper effect. So 120 gpm minimum flow rate. At best (short run), 2" pipe maximum flow is 90 gpm. The 3 HP single speed pump ran very loudly. So the builder replaced it with a VS pump which they adjusted speed until it ran quietly. That worked for the sound, but the sheer laminar effect was completely lost. Suction line was 2" pipe, about 30 foot run. Another is on booster pumps for cleaners. I've had calls to replace the motor because it was running very loudly. I recognize the sound instantly and go check the wall fitting. It's always the pressure relief valve has come apart. One customer called BS on me (understandable) until I told him to listen to the pump as I pressed my hand over it to restrict flow. Pump immediately regained normal sound. That again is cavitation. With that new "hole" in the return to cleaner, it allows a much higher flow rate which reduces restriction downstream from the booster. Tech tip: I always carry a standard PVC 1" threaded plug on me to replace the broken over pressure device. About $1.50.

People ask such good questions!

yea. i probably went overboard. replaced my pentair vs which was a 1.5 with a black and decker vs 2.0 after the drive blew in the pentair. haven't noticed any safety issues. however i have been running the max speed at 2500 as opposed to 3000 as 3000 just led to cavitation. running it at 2500 gives me around 45 gpm after the heyward cartridge filter. so far so good.

Great video as always!

I had a problem this year with my pool pump not pulling the water and also some leaking around the pump. It was repaired and the pump motor was first rebuilt and then it was replaced. My pool guy handled all of it. Now ever since the pump was replaced it seems to lose a lot of water. I have to fill my pool up every day. It will lose from above the middle of the skimmer all the way to the bottom. We don't have an answer as to what it is. They have pressure tested the line and also we have let it sit and it does not lose water past a certain point. The most water lost is when the pump is running. I had thought maybe the hot summer but even this fall in cooler weather it is doing the same thing. Could it be from a pump that is too powerful. This one seems very powerful?

What if the pool is too powerful? What could be the best methods to reduce the flow a little? A ball valve ?

I am so confused… what size pump do I need for a 10 foot x 10 ft x 28 inch deep round poly stock tank pool that I am building with a stone surround and a stainless steel waterfall spillway embedded in a retaining wall? I am thinking I will probably have the waterfall on a separate pump

Let's use 2" pipe for this conversation. It may help others to ONLY talk in GPM, since we can easily read the output from a store bought flow meter in series to a discharge pipe. Dealing with water velocity in feet/s and most folks get cross eyed at the thought of doing the math conversion. You are referring to ONLY one suction line where "6 feet/s fluid velocity" or "68 GPM" is the max, correct? I think some are getting confused by their "total" GPM (at discharge), even though they have more than one suction line. The most rudimentary of pools has just one skimmer or 1 suction line, BUT that is so rare. Adding a 3 HP pump (or using an unchecked high RPM from that pump) would certainly be dangerous, but even a 3HP pump can be used in variable mode and just use a low RPM without any danger, just keep an eye on the flow meter. Taking into consideration contemporary pools with 2 main drains (that tee together to make 1 suction line prior to the suction manifold), and 2 skimmer suction lines - three lines total (at the manifold). Now having 68 GPM (discharge) divided by 3 = 23 GPM per suction line, which is now, WAY below the safety velocity threshold. And where the main drain pipe "tees" off to connect the two, each one of those individual pipes will have even LESS GPM flowing through them - that should be noted as many are still afraid of main drain suction safety. As mentioned, there are a lot of moving parts to this, but it should be noted that just because there are more 3 HP pumps out there, it doesn't mean they are causing harm. Even at a WHOPPING 200 GPM total at the discharge line, that is just 67 GPM at each of the 3 suction lines, which is the maximum (per line). Though only about 80 GPM is the max efficiency you get with 2" piping and 200 GPM would shred your filters. You can use a higher HP and lower RPM (1,700) to turnover 25,000 gallons 3 times daily at a constant total 52 GPM (or only about 17 GPM per each of the 3 suction lines). Many folks use higher HP pumps these days to take advantage of the lower wattage used at lower RPMs to save $100/mo or more running their pump 24/7 (though the pump may cost $2,800, these new magneto pumps last even longer).

Can a strong pool pump cause bubbles in the pump, my run is long 50ft, very old cement pool

I have a few pools that after a filter cleaning the filter pressure is still over 30 even with all return lines open. I lowered the max pump speed so that the pressure is around 25PSI. I have assumed that this is because the pump is over sized.

Is the Intex sand filter pump self priming? And can you make a video about it?

can I use a swimming pool pump on a well pump system?

Thanks for the information. Besides the more powerful pumps being a potential safety hazard, I have read that a too powerful pump in a cartridges based filter system would make the filter less efficient. Not sure if true or not, so can you confirm?

I am looking to install a small plunge pool probably about 3500 gal. Do they make a VS small pump for a pool this size? Thank you I really appreciate your videos

I’m shopping for a new VS pump for my dying old 1hp single speed pump in a 14k gallons pool with pop up cleaning heads and 2” piping but almost all sellers are pushing me to buy a 3hp pump. I researched and found that a 1.5hp VS pump will be ideal for my pool because it uses less energy and is strong enough for 14k gal but those same sellers are saying my research is wrong. Am I wrong or are they just trying to get rid of their inventory?