Filter Backwash Point with VSF Pump

[ajw22]

TFP recommendation for backwashing or cleaning a filter is when the filter PSI rises by 25%. That worked fine when we used single speed pumps and normal filter pressure was 15+. A PSI rise of 5 or more was easily visible.

Running a VS pump at low speeds can give low normal filter pressures. My normal DE filter pressure at 1600 RPM is around 6-7 PSI. I am finding the filter pressure barely increases before I get reduced flow and my IntelliChlor starts indicating LOW FLOW.

My VSF pump and InteliCenter displays the flow. I am finding using a decrease in the flow is a better indicator of the filter getting dirty then the filter PSI.

My clean filter flow rate at 1600 RPM is 22 GPM. As the filter gets dirty I can see the GPM dropping to 16 or so. The last 2 days a big storm rolled through with lots of wind and dirt blown into the pool. Today I was looking at the IntelliCenter and saw a flow of 10 GPM and the LOW FLOW message was blinking on and off. Looking at the filter PSI did not show a big change to indicate the filter needed cleaning.

Today was the second backwash this season since I opened the pool in April.

I am using the flow indication to show filter buildup and when cleaning is required. If you have a VSF pump that displays GPM you may want to monitor that in addition to your PSI.

 

[Newdude]

My normal operating pressure is 3 psi. I'd never spot a .75 increase.

Allen, have you run at full throttle to compare the PSI increase in a higher range ? (Basically mimicking the way it used to be)

 

[ajw22]

Allen, have you run at full throttle to compare the PSI increase in a higher range ? (Basically mimicking the way it used to be)

When run at RPMs of 3450 then I get around 28 PSI of pressure and I would see a large PSI rise when the filter is dirty. But I never run at close to that. My max RPM when my heater runs and I want over 40 GPM is 2600 RPM which gives around 45 GPM.

I walk by my equipment pad and check things with a glance - three green lights on SWG, check; filter PSI about 7 - check; no leaks - check; no strange sounds - check. And when I look at the IntelliCenter display to check water temp, adjust heater, check salt, and CHECK FLOW GPM, it all takes less then 3 minutes to do a daily pool check.

Checking filter status by needing to increase RPM to 3450, check PSI, reduce RPM back is a bunch more work then just glancing at pump flow GPM which seems to be an equally good indicator. And I can do it from the comfort of my easy chair and not trek outside to the equipment pad.

 

[proavia]

I've used a Hayward VSP for about 10 years now and there is no flow measurement, only rpm. My pump mostly runs at 1100 rpm. About every week or two I run the pump at 3200 rpm (my present priming speed) for a few minutes to check the filter pressure. I use that as my gauge to know when filter pressure rises 20%-25% above clean pressure. It's only a couple button presses to change the rpm.

I don't have automation and use the pumps control panel and built-in schedule function.
My pump runs 24/7. Twenty hours per day at 1100 rpm and 2 four hour schedules at 2800 rpm for my IFCS. The SWG flow switch closes at 900 rpm, so running at 1100 rpm and greater allows the SWG to produce continuously.
Speed 1 = 1100 rpm
Speed 2 = 1600 rpm
Speed 3 = 2800 rpm
Speed 4 = 3200 rpm

 

[Newdude]

Checking filter status by needing to increase RPM to 3450, check PSI, reduce RPM back is a bunch more work

For me it's one button press (4th preset), check filter gauge, and one button press (1st preset) back to low rpm.