Is a pool pump speed controller necessary ?

[Teapot]

Hi Hsiao

That is running at full speed it's 3/4 kw down to a light bulb

Hsiao, whilst you have a power meter fitted, as I have said all the way through you need a flow meter to tell you exactly what the pump is pushing through the system.
Pumps are made with an impeller of the right size and shape to operate at the given RPM. yes you can vary that to a point but too slow and they become inefficient and the flow through the system will be too low to achieve clearing the water. With low batherload pools you can get away with a lot but these are schoolboy errors to assume you can just wind down the pump.
I have had people do just that and they lost control of their pool and had to turn the system back up. Guessing only, you could wind down the RPM by 33%-about 50% of the power safely but with a flow meter you get the real data and you will see when using low power how quickly the flow drops when the filter begins to get dirty, along time before the gauge shows an increase in pressure.

Pool equipment was never designed to be efficient so if you tinker you can end up worse off. When I setup a system the most important part is to monitor the flow at given pump RPM and from that we can setup what works.

I have spent my time designing super efficient pool systems and I know what will work and what won't. My pool runs at 60-69 watts per hour at the proper flow rate to turn over the pool. I am working on a new filter that should improve on that even more and actually backwash properly.

[Hsiao Chang]

Hi John, there will be a flow meter installed for me, i will adjust the speed accordingly to find the right flow. according to your experience, may i ask how many turnovers do you think appropriate per day for a pool with low batherload please?

[Hsiao Chang]

Hi Hsiao
Can you post details and costings for others as that seems excellant and can offer alternatives
That is running at full speed it's 3/4 kw down to a light bulb

Hi Dennis, there was a technical guy who explained me an affinity low, which i googled afterwards, yes, only turning down the speed a little bit, power consumption
drops a lot. that's why when a speed reduced by 50%, power dropped by 80%. and for proper filtration, you dont need a backwash speed.
I bought it through a friend, who knows the manufacturer, so i got a better retail price, 300 USD. but as John put, you will need to have an idea about the actual flow running
through the system, so it's not necessarily you are saving 80%.

[Teapot]

Hi John, there will be a flow meter installed for me, i will adjust the speed accordingly to find the right flow. according to your experience, may i ask how many turnovers do you think appropriate per day for a pool with low batherload please?

Thank you Hsiao, nice to be listened to.
You need to take account of the min flow your heater can have.

From my earlier post I mentioned Gage & Bidwell who mathematically calculated the dilution figure and therefore the filtration level for a given number of passes through a filter.

Gage & Bidwell's law of dilution gives us some expectations on how much water actually makes it through the filter. 1st turnover 63%, 2nd 86%, 3rd 95%, 4th 98%, 5th 99% of the water filtered. There are alternatives but they are all pretty close to one another. Personally I am happy with 4 turnovers per day and that fits nicely with the energy usage.

Is the pool outdoors or indoors?
If it's out doors uncovered then the skimmers only work when the pump is running. So when it's not running dirt enters, sinks to the bottom and requires manual removal.
If you run your pump 24hrs per day then the dirt will get collected and water filtered leading to much cleaner water and less chlorine usage. We would all do this if it were cheap enough but we don't because of the expense, you are now in a different league where it might not cost anymore to run for 24 hours. Indoors you may well benefit from less pump run time.

110m3 turned over 4 times like I do, means a flow of 18.33 m3/hour and that is impossible through your filter. Turned over 3 times, means a flow of 13.73m3/h still impossible through your filter. Turned 2 times, means a flow of 9.16m3/h might just be possible through your filter. Hopefully you see why I said add a second filter?
So outdoors or indoors is very important, covered or uncovered.

I see a lot of pools, I have customers, not all take notice of me. One in particular turns over his pool just once a day, he uses more chlorine but it's swimable, not as clear as mine (1.2 NTU's) closer to 9NTU's, Another pool I converted was 12NTU's when I first saw it and that was hazy but in those days the owners knew no different.
Hope that helps.

Dennis, in our country the units are about £349, sorry I have actually misplaced my price sheet for the minute.

[Hsiao Chang]

Hi John, that's what i am here for, to listen to professionals as i honestly have no idea about the pool system. always grateful for the things you and Dennis told me.
I remember you saying my pump is oversized but filter undersized, my understanding is, because of this, i need a filter to better match flow of the pump can offer, hence 2x450mm filter recommended, did i get this right please ?

[Hsiao Chang]

Hi Hsiao
Can you post details and costings for others as that seems excellant and can offer alternatives
That is running at full speed it's 3/4 kw down to a light bulb

Hi Dennis, I would suggest you get one of this speed controller too .

[Hsiao Chang]

" We all have a duty to lower our Co2 output, the oceans are becoming more acidic because of Co2 and it's so unnecessary."

----- Hi John, remember this was what you said to me/us, i watched a BBC documentary "chasing coral" , says about CO2 impact on oceans and corals. i recommended to my co workers, hopefully more and more ppl will have the awareness of protecting environment.

[Teapot]

Hi John, that's what i am here for, to listen to professionals as i honestly have no idea about the pool system. always grateful for the things you and Dennis told me.
I remember you saying my pump is oversized but filter undersized, my understanding is, because of this, i need a filter to better match flow of the pump can offer, hence 2x450mm filter recommended, did i get this right please ?

Hi Hsiao, Yes that's correct, I now usually fit 2 filters rather than one large one as they take up less space and easier to backwash as I fit slide valves to each inlet and outlet so I can backwash one at a time/service one at a time.

Please let me have your data when you get the flow meter fitted (pump flow vs gauge pressure, rpm and watts) as it helps me build a database. You may need to get a lower reading pressure gauge for normal running.

[Hsiao Chang]

Hi John, i am currently working very far away from home, so i will need sometime before i can send you the data, please bear with me.

[nick56]

Yeah, its neccesary to controll speed of pool pump
For enjoying holidays with summer pool.....

[Teapot]

Yeah, its neccesary to controll speed of pool pump
For enjoying holidays with summer pool.....

Not actually sure what your point is? Maybe you could come back and explain what it is you are referring to

[Teapot]

Ethan, what has your post got to do with speed control on a pump? Now be a good chap and go away, nobody wants your acoustic covers.

[Ethan Miller]

Recently my wife and I built a swimming pool in our backyard and from a professional standpoint this was such a great learning experience. Building our pool allowed me to test out many of the pool products that I have recommended over the years. During this process I found there were products that I absolutely loved, but at the same time there were a few products that I have recommended on a daily basis that I would not recommend in the future again.

[Teapot]

I only recommend products I or my customers have personally tested. Its worrying if you have recommended products that when you actually tested them failed. That should be a warning to forum folk not to listen to some people and their views.