Need a gut check with changes in setup

[seekingsand]

I'm still very new at this and would like either confirmation that I'm thinking this through correctly or please set me straight.

First time pool owner as of Nov 2020. At that time, it had two single speed pumps (2HP for spa jets, 1HP for pool) and a sand filter. Soon after, we added a SWG and changed to Pentair CC100 cartridge filter.

A few days ago the 1HP pool pump died. I replaced with a 1.5HP Intelliflo VSF. During installation I realized that although everything else is 2", the pump to filter connection was 1.5". Don't know why, maybe it was a relic of the previous sand filter that the installer didn't change but while installing the new pump I charged it to 2" to match everything else.

Now I'm trying to program the pump and it makes sense to me to program using flow rate rather than RPM since the pump is capable of it. So I'm trying to figure out the max flow rate that I could be using for the 3 or 4 hours per day that I choose to run it for skimmer action.

I decided to work backwards from determining the max flow rate for my system. Everything is now 2" and depending where I look I find a max flow to be approximately 75 GPM. The CC100 filter lists max 100 GPM but digging deeper, it's specifications say that 0.5 GPM per sqft (50 GPM) is preferred.

If I hadn't dug into the specs I would have ran with 100 GPM for the filter and considered the 2" max flow to be the limiting factor. I have no idea what the flow was in the system prior to swapping out the pump.

I understand that ultimately (respecting max flow) the settings I choose are up to me and what tends to work for our pool but I'm curious what others think about the recommended 0.5 GPM/sqft for the filter versus the far easier to find 100 GPM spec.

Is anyone concerned that 50 GPM may be too low? I understand "buy the biggest filter you can afford" (at least in hindsight.. we bought the CC100 based on the recommendation of the person who sold and installed it). Do I need to consider upgrading the filter?

Again I think this all comes down to "if 50 GPM is enough to operate the skimmers effectively, there's no problem" but I'm still curious what others think to help me learn more...

 

[BowserB]

I run 1650 rpm from 2-3:45am and again from 9:15am to 7:45pm. I'm just going for the speed that is adequate for the IC-40 SWCG. The skimmers are sucking in water all the while and collecting those annoying wax myrtle leaves. Note if you have a main drain running with the skimmers, you can increase skimmer flow by at least partly closing the main drain. With a VSP you can run a lot longer for less electricity at lower speed. According to Pentair running at 1/2 maximum speed uses only 1/8 as much electricity. Other people here run as slow as 1200 rpm effectively. Running longer also means you're creating chlorine longer and running water though the chlorinator--which apparently is kind of a big deal for SWCG. I can't imagine needing even 50 GPM. The IC series Pentair SWCGs call for around 25gpm +/- 5gpm and with over 80gpm a bypass loop is required (owners manual p.5)

Last, you have 21000 gallons and a C&C 100 filter? Seems really small for that much water. Unless that's 21000 liters, in which case that's only slightly smaller than I would want, since I don't enjoy cleaning filter cartridges and all the hardware stuff that goes with that chore.

 

[seekingsand]

I run 1650 rpm from 2-3:45am and again from 9:15am to 7:45pm. I'm just going for the speed that is adequate for the IC-40 SWCG. The skimmers are sucking in water all the while and collecting those annoying wax myrtle leaves. Note if you have a main drain running with the skimmers, you can increase skimmer flow by at least partly closing the main drain. With a VSP you can run a lot longer for less electricity at lower speed. According to Pentair running at 1/2 maximum speed uses only 1/8 as much electricity. Other people here run as slow as 1200 rpm effectively. Running longer also means you're creating chlorine longer and running water though the chlorinator--which apparently is kind of a big deal for SWCG. I can't imagine needing even 50 GPM. The IC series Pentair SWCGs call for around 25gpm +/- 5gpm and with over 80gpm a bypass loop is required (owners manual p.5)

Last, you have 21000 gallons and a C&C 100 filter? Seems really small for that much water. Unless that's 21000 liters, in which case that's only slightly smaller than I would want, since I don't enjoy cleaning filter cartridges and all the hardware stuff that goes with that chore.

Thanks for the reply and you read that right... Somewhere around 21,000 gallons. I don't know exactly but based on multiple calculations I've done I always end up around 20,000 to 21,000 including the spa. Not sure what to really call it, there's no heater, just jets.