Is a pool pump speed controller necessary ?

[Hsiao Chang]

Hsiao, we need to know the diameter of the plumbing, the size of your filter (dia), type of filter and length of plumbing run approx. You may want to add these details to your profile.
The correct flow for your heater will be spec'd in the manual, often around 5m3/h. Is your heater plumbed on a bypass loop so you can adjust it?
You should get a flow meter to check the best flow to turn over your water. 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.

Hi Teapot, thanks for your input, sorry i didnt realize this thread has come to 2nd page.i will update my profile after this reply.
Pool: 110 CBM
Pump: 1.5hp Qmax: 350l/min; Hmax: 14m
Connection: 50mm
Sand filter: 450mm
heatpump: 33kw output @26C/26C

[Teapot]

Hi Hsiao, Thanks for the information. Yes you can save quite a bit by slowing down your pump. If I were building your setup you would have two 450mm filters for 110 CBM which would filter better and drastically cut your headloss.
More later as I have to go to work.

[Denniswiseman]

I have a 27kw heat pump and my minimum flow rate is 9 cubic metres hour
My .5hp pump gives me a flow rate of 10.8 cubic metres hour
Your pump has a flow rate of 21 cubic metres hour so I would expect you should be able to reduce your speed quiet a bit without affecting your heat pump check your minimum flow for your heat pump to work bearing in mind that you can always turn it up
Generally speaking you should match your pump to your filter (check your filter flow rate) as to great a flow doesn't filter as well because it is forcing the water through and not filtering
Slowing the flow will help filtering

[Teapot]

The flow rate stated on the pump is at zero head, on a pool setup with a small sand filter like Hsiao's, I doubt if it's actually flowing any more than 10m3 or a bit less. Forget what manufacturers say they are just in competition with other manufacturers.
This week I removed a 2HP pump from a small pool with a 600mm (24") sand filter and that was only flowing at 10.3m3/hr. That's why I have recommended a flow meter, the only real way of seeing whats actually happening and vital when you go to multi speed pumps with low energy.
Hsiao, what does your pressure gauge read?

[Hsiao Chang]

Thanks you Dennis and Teapot for your information.
The pressure gauge reads 12 PSI. is there such a thing as an appropriate pressure reading given my pool setup please ?
why would you recommend 2 450mm filters for a 110 pool please ?

[Denniswiseman]

Thanks you Dennis and Teapot for your information.
The pressure gauge reads 12 PSI. is there such a thing as an appropriate pressure reading given my pool setup please ?
why would you recommend 2 450mm filters for a 110 pool please ?

12 psi is OK for a clean system, however when the pressure rises 20 to 25% higher it's time to backwash
The bigger the filter is better
Normally you match a filter to the pump so that you aren't trying to push to much water through a filter which doesn't filter properly. Check your filter recommended flow rate and the flow rate of the pump
Apart from reducing your electricity bill, pump speed will also reduce your flow rate
It's a myth that you need "X" amount of water turnover, all you need is enough to clean, skim, run SWCG and mix chemicals

[Teapot]

Hi Hsiao,
1st answer: To run efficiently the lowest possible positive pressure is the best, pressure above that is just wasted energy through friction. However your pump would most likely cavitate unless setup carefully. Some pump controllers run a flat out cycle to achieve pump prime then onto a reduce speed as set by the operator. Others allow you to set the start up speed so you can slow start to lessen cavitation issues.

2nd answer: I didn't ask how many bathers use your pool and if it is indoor or outdoor? I recommend two filters for that size pool based on the maximum flow of the filter and your likely pool water turnover rate with the surface area of the filter before it clogs. Others have one big filter but they generally take up too much room and it's cheaper to add another filter of the same size you have now than buying a larger filter. Backwashing is also easier if you have isolating valves for each filter and variable speed pump.

By example, I have a customer with the same size outdoor pool as you and around 16 bathers at any one time. This pool uses a big Triton TR140 filter and my very special setup. Technically the pool needs to turnover every 4.5 hours and we can do this on 500 watts. However slightly slower filtration produces better filtration results and the customer actually runs it on 126 watts which gives him a flow 15m3/h at a filter pressure of 0.5 PSI.
This is a massive saving on the original 2.2kw pump which used around 2300 watts.

I hope that helps, it takes time on forums to get the whole picture, It's easier when I am with a customer and can asses the whole setup, nearly always beginning with the flow meter. I have done flow tests on lots of pools and record the data and customers are usually surprised at their results not being anywhere near what they thought or the pump plate says. the pump performance curve which normally comes with the pump doesn't take into account the filter or the plumbing and they have a massive effect on the energy usage and performance.

[Hsiao Chang]

Thank you for your advice Dennis, so i will have regular check on the pressure .

" Normally you match a filter to the pump so that you aren't trying to push to much water through a filter which doesn't filter properly..."

my understanding to this is , when you are setting up a pool, you decide on size of a pump first, then a filter.

Factors to consider when sizing a pump:
a).minimum flow rate (decided by pool volume/ turnover ) ;
b). total head ( which is the total friction of piping system, depends on length of pipes, diameter, number of turns etc ).

Factors to consider when sizing a filter:
refer to flow rate for the pump, but the bigger , the better.

[Hsiao Chang]

Hi Teapot ，
To answer your question :basically there are 6 ppl using the pool, some weekends around 10 ( not quite often ).

your customer's case : 110 M3 pool, turnover 4.5hr 500w , with same size pool, mine uses a 1.5hp pump, that's quite an oversized pump , am i correct ???
I suppose I do need a pump speed controller then ?

it's a little frustrating that i spent more money on a big pump, and in order to bring down cost of this big pump,
i need to spend more on a speed controller... is there a simple way or a general rule of thumbs for ppl properly sizing their pump rather than wasting money , please ?

[Denniswiseman]

Thank you for your advice Dennis, so i will have regular check on the pressure .

" Normally you match a filter to the pump so that you aren't trying to push to much water through a filter which doesn't filter properly..."

my understanding to this is , when you are setting up a pool, you decide on size of a pump first, then a filter.

Factors to consider when sizing a pump:
a).minimum flow rate (decided by pool volume/ turnover ) ;
b). total head ( which is the total friction of piping system, depends on length of pipes, diameter, number of turns etc ).

Factors to consider when sizing a filter:
refer to flow rate for the pump, but the bigger , the better.

Yes you have the right idea

[Teapot]

Hi Hsiao, don't be upset, whilst a low power setup works for filtration cycle don't forget you need the extra power to backwash properly or your filter will build up with debris over a period of time.
Also the example I gave above is a bespoke system I built, it was to illustrate what is possible, your setup with the small filter and other different components would not be as good but the point is you have recognised that big savings are possible, that is quite away ahead of millions of other pool owners.

As I said in an earlier post, manufacturers are in competition with each other for your money so they overstate what the capabilities of their equipment in real world scenarios. My rule of thumb for filters; half the flow the manufacturers tell you you'll get! Single speed pumps are generally too fast for filtration and too slow for backwash. Using oversized pumps and under sized filters is a typical American setup. That way of working generally means the oversized pump is hampered to a point that the flow is only a little fast for filtration but oh boy you are straining the pump and burning electricity. We all have a duty to lower our Co2 output, the oceans are becoming more acidic because of Co2 and it's so unnecessary.

[Hsiao Chang]

Thank you for your advice Dennis, so i will have regular check on the pressure .

" Normally you match a filter to the pump so that you aren't trying to push to much water through a filter which doesn't filter properly..."

my understanding to this is , when you are setting up a pool, you decide on size of a pump first, then a filter.

Factors to consider when sizing a pump:
a).minimum flow rate (decided by pool volume/ turnover ) ;
b). total head ( which is the total friction of piping system, depends on length of pipes, diameter, number of turns etc ).

Factors to consider when sizing a filter:
refer to flow rate for the pump, but the bigger , the better.

Yes you have the right idea

It's a bit embarrassing to say,but i do have a better idea of the whole system now and it's all because of your help , thank you Dennis

[Hsiao Chang]

Hi Teapot,
Thanks for your explanation. I wish i had known what you and Dennis told me earlier, now i am more positive on getting a pump speed controller, as i wasn't sure what the sales reps told me. Have you had any experience with this kind of product or any particular brand you have heard of please ?

I have no idea how many pool users there are globally, but yea, think of that, if each pool user can save half energy , we are saving a whole lot .

Once i have decided on one, i will post back how it works.

[Teapot]

Hi Hsiao,
Yes I have fitted two, the first was a Clever-Pool Pump Inverter, very straight forward. That's the one I mentioned that powers up full speed to obtain prime and then reduces to your set program. It has 4 settings so I imagine that's the one you were mentioning.
The second, was the Invertek Optidrive E2, this allows slower start ups and more customisable programs but is more complicated to set up.

Don't forget what I said about a flow meter, it could be ultrasonic, hall effect, Flow vis or the traditional flow meter. In my opinion a must when doing this work. If budget is really tight then a low range gauge fitted to the filter will be easier to watch for filter clogging. My gauge is a 0-15PSI but with the capability of your pump a 0-30PSI. As you wind down the speed of the pump and stop wasting so much energy the pressure on the gauge will drop and you need to backwash when it increases slightly. My system runs on 0.5 PSI and I backwash when it rises to 2.5-3PSI. When using lower power the flow drops off quite quickly as the filter begins to clog so that is the best way to see whats happening. In pools with sand filters and big pumps dirt, skin cells etc literally get sanded down until they are small enough to make it through the filter back into the pool. Daft isn't it, pay lots to do little!

What I call a standard setup, 0.75hp and 500-600 dia sand filter produces just over 2 tons of CO2 in a 6 month season mine 126 KG ok you'll be probably double my figure but you were starting from a much bigger pump. Multiply that by the number of pool owners and its colossal. You will save the cost of pump controller in the first year I would expect and have better clearer water.
Good luck with the project and please let us know how you get on.

[Denniswiseman]

I haven't had any experience of pool pump speed controller but this Forum should be able to help you

As I previously posted that forum will have a lot of people experienced with different types of pump control and should be able to offer an appropiate speed controller for your region (I take it that you are in the states)