Pump runtime - 24/7 or not?

[1635blueaspen]

I have a brand new salt water fiberglass pool. The volume is 10,000 gallons and the pump is a Pentair Intelliflow VSF.

Our weather has been extremely hot (100+) lately and we are projected to be 95+ and sunny for awhile.

The pool company set the pump up to run two schedules. During the day they have the pump running at 2300 rpm and at night they back it down to 1750 rpm. Water looks great and is testing good. The iChlor 30 SWG is set to 45%.

My question is this: Is a 24/7 runtime necessary? And at that, could I back the rpm down with such a small pool volume? Just looking to save some kwh.

 

[ajw22]

The pool company set the pump up to run two schedules. During the day they have the pump running at 2300 rpm and at night they back it down to 1750 rpm. Water looks great and is testing good. The iChlor 30 SWG is set to 45%.

Running your iChlor at 45% for 24 hours in your 10,000 gallon pool will generate 5.4 ppm of chlorine.

The average pool uses 3-4ppm per day.

So your FC generation is probably more then necessary,

What is your CYA?

My question is this: Is a 24/7 runtime necessary?

No, not necessary. You can reduce your pump runtime and adjust your SWG %.

And at that, could I back the rpm down with such a small pool volume?

You need to find the RPMs where the iChlor flow switch no longer is on and then add 200 rpm. That is your minimum RPM for your setup. I don;t know if your PB did that when he set it at 1750.

Just looking to save some kwh.

Your VSF pump can display the watts used. See how much of a difference in watts there is in lowering your RPM from 1750.

You will find at the low speeds you are not using a lot of kwh to save...

 

[wireform]

You can also run the pump as mentioned above at the slowest to satisfy SWCG and run it 24/7 at the very efficient setting and tweak down the SWCG to replace the daily loss.

 

[1635blueaspen]

Thank you both for the replies.

Yes the VSF pump displays the watts and this is what got me thinking about adjusting it down. The 24/7 at a lower speed seems like a better idea to me but I'll have to check the SWG rpm level.

Currently my CYA is very low at 20. I have some CYA on the way to dissolve in this week.

The idea to check the SWG minimum rpm is a great one. I will work on that today!

Is that pump spreadsheet available somewhere?

 

[wireform]

Without a having the CYA up at SWCG levels the uv will get that new chlorine just producd before the pool can benefit from it.

 

[ajw22]

Get your CYA up to 60 or above before you begin reducing SWG % or pump runtime.

 

[ajw22]

Is that pump spreadsheet available somewhere?

@PoolGate did the spreadsheet for his pool and may be willing to share it as an XLS file.

 

[PoolGate]

Pm me your email I'll email it the forum won't let me upload it.

 

[1635blueaspen]

I took some measurements on the pump tonight using just the four preset speeds to get an idea of what my options might be.

750rpm - 36 watts - 24gpm - Green SWG Flow LED
1500rpm - 181 watts - 23gpm - Green LED
2350rpm - 665 watts - 41gpm - Green LED
3450rpm (max speed) - 2015 watts - 62gpm - Green LED

The builder has it set to run 24/7 at 2300rpm 9AM-9PM and 1500rpm 9:02PM-8:58AM.

I cannot explain the 24gpm at 750rpm being basically equal to the flow at 1500rpm. But why wouldn't I just run it 24/7 at 750rpm? Does chlorine generation vary based on flow rate? Or strictly pump run time?

 

[Newdude]

But why wouldn't I just run it 24/7 at 750rpm?

That may be too low to skim. But if the skimmer doors are flapping away at 750 RPMs, then you're all set.

Also, with that low of a RPM, you may be real close to where the SWG shuts off from low flow. We like to find that spot (use the directional arrows to go down in 10s) and then add 100 RPMs to account for the filter getting dirty over time and decreasing the flow.

Does chlorine generation vary based on flow rate?

Nope. It needs enough flow to turn on. Then it has on/off cycles based upon the % you set.

Or strictly pump run time

% of runtime. If you ran 24 hours at 50%, the SWG would produce for 12 hours a day with on/off duty cycles. 25% would produce for 6 hours, etc etc.