RPM

[neptunes]

Moderator note - Split from here: Optimal flow rates for variable speed pumps

The heater is more efficient at higher flow rates, up to about 80 GPM, but the difference isn't all that large and the pump is less efficient at those flow rates so it kind of cancels out. I would use 45 or 50 GPM for the heater, just to make sure you aren't right near the lower limit.

Assuming the waterfall is plumbed the way most of them are, which the waterfall pump having it's own separate suction, then the main pool pump doesn't need to be on at all while the waterfall is running.

I'm less sure about the SWG flow rate. That is the highest minimum flow rate I've see for a residential SWG cell. It is not clear to me why they are asking for that flow rate. There are some possible reasons that are fairly important, or they might just be overly cautious.

I don't have any heater or spa or SWG -- a plain and simple rectangular pool of about 16,000 gallons with one skimmer. I am in South Florida and this is an open air pool so gets a fair sprinkling of leaves, seeds, pollens and bugs. My Smartpools wall scrubber robots takes care of the debris quite well and also helps mixing the pool water when I run the robot -- which is , may be, twice a week. My variable speed pump outputs about 30 GPM at 1500 RPM. So am I safe running the pump at 1500 RPM for 10 hours a day? Why do I need to run the pump at higher RPM? And if I do not need higher RPM -- why do I need a variable speed pump? I suspect that the skimmer does not pull the larger debris at this RPM.

If I do need the higher RPM, can anyone suggest how should I program my pump between the different RPMs? These problems have confused me for a long time.

Many thanks for your help

 

[RobbieH]

Re: Optimal flow rates for variable speed pumps

See my thread here:
So, I've been doing some math (electricity usage)...)

If you want the spreadsheet I put together to track this, I'll PM you my email address.

FYI, I turn my pool just under once per day, and run 24/7. It is the most efficient for my needs. The spreadsheet I have can show you what is most efficient for you.

- - - Updated - - -

You can program the VF to run at the slow rate most of the time, then you can program Feature 3 to run at a higher speed for an hour or two to give your skimmer what it needs. It will automatically shave time off the low flow time to compensate.

 

[pooldv]

Re: Optimal flow rates for variable speed pumps

I am going to ask mods to split this to your own thread.

I run my pump at 1100 rpm to skim, filter and make chlorine with the SWG. It uses 150 watts and does a fantastic job of skimming and keeping my pool clean. I run the pump 24x7 in spring and fall. 10ish hours in winter, 24x7 if freezing. And 14 or so hours now, sun up to sun down so solar heat can turn on as needed. At 10.25c/kWh I can run the pump 24x7 for 12 bucks a month.

My SWG is on its own timer and usually runs 6-8 hours a day.

 

[mas985]

So am I safe running the pump at 1500 RPM for 10 hours a day?

Sure but you might be able run at lower RPM or even less hours if you are willing to experiment. Every pool is different so there is no set answer. Some on the forum run for less than an hour a day and have satisfactory results. Also, the run time study in my sig, which was done in FL, shows that there is very little water quality improvements after only 2 hours of run time.

Why do I need to run the pump at higher RPM?

If everything is working ok, you don't. Many people find the skimmers may not collect debris well enough at lower speeds so they run higher. Same with some pool cleaners.

And if I do not need higher RPM -- why do I need a variable speed pump?

Short answer is nobody "needs" a variable speed pump but there are reasons to own one. Multiple speeds are surely one reason but for many pools, this is not needed. Higher efficiency is another reason but if you don't pay a lot for electricity, a two speed pump can be just as economical if not more so because of the lower up front cost.

 

[neptunes]

Many thanks RobbieH, pooldv and mas985

So, I have programmed the pump as follows:
8 am - 9am : 3000 rpm
9 am to 12 noon: 1500 rpm (30 GPM)
3 pm to 4 pm: 3000 rpm
4 pm to 7 pm : 1500 rpm

This ought to circulate the volume of my pool at least once every day.

Let me see how it goes. I also run the pool robot twice a week.

 

[RobbieH]

On a VF, you can just tell it your pool size, how long you want it to run (24/7 in my case) and how many turnovers you want. Then you can program feature 3 (and feature 4 if you need to) to run at a given GPM for X minutes to turn more. The VF will take over from there and do all the calculation for you.

Now, let's say you want less than a full turnover. Just lie to the pump about the size of your pool.

 

[mas985]

This ought to circulate the volume of my pool at least once every day.

Just so we are clear, there is no reason to turnover a pool once per day. I only turnover my pool 1/2 each day in the summer and 1/4 in the winter.

Pool School - Determine Pump Run Time

 

[neptunes]

Just so we are clear, there is no reason to turnover a pool once per day. I only turnover my pool 1/2 each day in the summer and 1/4 in the winter.

Pool School - Determine Pump Run Time

Thank you Robbie and mas985, You guys give me extra confidence. I will try shorter run time and see how it goes.