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Thread: one long segment or multiple short segments of pump run time?

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    iam4iam's Avatar
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    one long segment or multiple short segments of pump run time?

    First of all, let me warn everyone reading this that i tend to be an extreme over-analyzer. I'm sure that is the case again here, but I'd like to know what others think about my analysis, nevertheless.

    My pump is currently running non-stop, because the water was cloudy when I took off the pool cover. It honestly looked clear to me, and I had made a couple of FC checks and chlorine consumption is as expected this time of year (around 1 PPM/day with water temperature in upper 70s), but I had obviously forgotten what the water is supposed to look like. My wife came out and said she thought it looked a little murky, and she was so right. I looked back at a photo from last summer and was shocked (and mad at myself for thinking my water was clear)! So I turned on the pump and let it run. It has now been through 3 backwashes (at 16-20 PSI when starting at 11 PSI clean with DE)! I plan to run it until there is no increase in PSI for 12 hours, since it has occurred to me that one of the best indicators of water clarity is no increase in filter pressure. I am often asking myself, "Is the water really as clear as it could (should) be?" Now it seems that since I can't trust my eyes, I can rely on my pressure gauge.

    Experience has led me to the conclusion that 4 hours per day is sufficient to keep my pool looking good. In years past, I have broken this up into 4 1-hour cycles for two reasons:
    1) to maximize skimming effectiveness
    2) to maximize the effect of heat transfer

    Now i am considering just 1 4-hour cycle of pump run time for two (related) reasons:
    1) I can observe PSI at the beginning and end to confirm that there is no change in PSI
    2) Overall filtering efficiency may increase? (question explained below)

    By "overall filtering efficiency" I mean total amount of debris filtered out in 4 hours. I am picturing this as a definite integral of filtering rate over time. It is clear (and logical) that filtering rate is dependent on pressure and flow rate, which are inversely proportional (sort of). Since I learned from a previous post that flow rate decreases more slowly than pressure increases, it seems a moderate increase in pressure will also increase filtering rate. I have noticed that when the pump turns on, pressure is often 1-1.5 PSI less than it was at the end of the previous run cycle. (This makes no sense to me, but i attribute it to redistribution of filtering media when pump shuts off and then is turned back on.) Hence, the area of the integral I am picturing would be greater as 1 integral over 4 hours than 4 integrals over 1 hour each. Does that make sense?

    If you actually read this far without giving up because I am a nut case, thank you. Do you have any thoughts regarding my theories? Are they valid, useless in practice, both, or neither?
    ~18,000 gal (16x32) vinyl
    Hayward sand filter
    Circupool RJ45 SWG
    Hayward Max-Flo XL SP2305X7 pump (0.75 HP)

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    CJadamec's Avatar
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    Re: one long segment or multiple short segments of pump run time?

    When the pump is running the water in the pool starts a circular motion getting pushed by the return around the pool and back into the skimmer. Which is why if you are trying to float in the pool while the pump is running you can never stay in one spot.

    This circular motion brings all the surface debris to the skimmer to be cleaned and piles all the floor debris into neat little piles on the floor of the pool typically in the center of each radius on the ends on your oval pool.

    Each time you start and stop you pump the water has to start moving again and that takes time. If you leave the pump running for the 1 4hour period you should end up with cleaner water. Or so the voices in my head are telling me. Somebody may completely disagree with me on this.
    Chuck-
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    Re: one long segment or multiple short segments of pump run time?

    I,

    If your water is cloudy, it is much more likely a chemical issue rather than a filtering issue...

    How about letting us "over analyze" your water numbers...

    My gut says you are running your FC way too low.. But then again, I've been wrong several times in the last hour alone...

    If this were my pool, the first thing I would do is run an Overnight Chlorine Loss Test (OLCT).. just to make sure... Overnight Chlorine Loss Test

    If you are running your FC at the bare minimum, then running in 4 one hour segments would work better at keeping your FC level up... Running one 4 hour segment would mean your FC might burn off before the next SWCG run...

    Thanks,

    Jim R.
    17K Gal, IG, 20' x 25' Almost Rectangular Pool, Pebble finish, three rockport water falls. Pentair Equipment: EasyTouch 4 (now 8), IC40 SWG, 3 HP VS Pump, CCP520 Cartridge Filter.
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    Re: one long segment or multiple short segments of pump run time?

    I agree with parts of both responses

    Run for 4-hr period, and up your FC (matching the top side of the FC/CYA Chart recommendations)
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    CJadamec's Avatar
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    Re: one long segment or multiple short segments of pump run time?

    I suspect Jim is also correct. My voices concur.
    Chuck-
    15x30 AG, Pentair Superflo VS, 19" sand filter, TF-100 test kit
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    iam4iam's Avatar
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    Re: one long segment or multiple short segments of pump run time?

    Quote Originally Posted by Jimrahbe View Post
    I,

    If your water is cloudy, it is much more likely a chemical issue rather than a filtering issue...

    How about letting us "over analyze" your water numbers...

    My gut says you are running your FC way too low.. But then again, I've been wrong several times in the last hour alone...

    If this were my pool, the first thing I would do is run an Overnight Chlorine Loss Test (OLCT).. just to make sure... Overnight Chlorine Loss Test

    If you are running your FC at the bare minimum, then running in 4 one hour segments would work better at keeping your FC level up... Running one 4 hour segment would mean your FC might burn off before the next SWCG run...

    Thanks,

    Jim R.
    CYA = 80-90
    FC on 5/6 was 16
    FC on 5/14 was 8
    SWG was off between those measurements so no chlorine was being added, hence my calculation of -1 PPM FC/day, which is about normal for my pool in May. A daily FC loss of only 1 PPM seems good. I wouldn't expect less than that at current water temperature. I only do OCLT after a SLAM (which I have only had to do once in the last 4 years, fortunately). I guess I just hadn't been running the pump long enough during the end of April and beginning of May, so the water was not its ideal crystal blue. I didn't uncover the pool to look until last week. Since FC was never too low, and FC loss has been as expected, I was expecting clear water when I uncovered the pool, so my lack of water clarity seems to be due to lack of proper filter time, which may be due to lack of memory. The more I think about it, I may have experienced this in past years, but I just don't remember from one year to the next. My wife wouldn't doubt that for a second!

    The main thing I am looking for someone to concur on is that under the assumption that pool water chemistry is in good shape, one can gauge water clarity by lack of change in filter pressure, which doesn't require me to remove the cover for a visual inspection. This way I can know it is going to be crystal clear when I remvoe the cover for the first time, even. As I alluded to in the original post, it appears that I can't rely on my visual assessment anyway!
    ~18,000 gal (16x32) vinyl
    Hayward sand filter
    Circupool RJ45 SWG
    Hayward Max-Flo XL SP2305X7 pump (0.75 HP)

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    Re: one long segment or multiple short segments of pump run time?

    I may be taking the easy way out, but I would rely on your wife’s visual assessment!

    I wouldn’t assume that lack of pressure change means your water is crystal clear, without actually looking under the cover. We’ve seen many people in the forums who have had very clear green water, or pretty clear water with algae just beginning to grow.
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    Re: one long segment or multiple short segments of pump run time?

    +1 If you can’t clearly see a screw on your drain, it’s not clear.

    I do want to add two points though. I think it’s actually better for the pump to run a single cycle than four short ones. Starting incurs more wear on the pump.

    Secondly, I personally feel it’s best not to be stingy with pump run time. I kn ow lots of folks here like to see how little energy they can get by with, but filtering is one of the cheapest things you can do to keep your water crystal and avoid problems (provided your fc/cya ratio is kept...otherwise that’s the first and best
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    Re: one long segment or multiple short segments of pump run time?

    Quote Originally Posted by Swampwoman View Post
    +1 If you can’t clearly see a screw on your drain, it’s not clear.
    I do want to add two points though. I think it’s actually better for the pump to run a single cycle than four short ones. Starting incurs more wear on the pump.
    Secondly, I personally feel it’s best not to be stingy with pump run time. I kn ow lots of folks here like to see how little energy they can get by with, but filtering is one of the cheapest things you can do to keep your water crystal and avoid problems (provided your fc/cya ratio is kept...otherwise that’s the first and best
    +1! I second
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    Re: one long segment or multiple short segments of pump run time?

    Based on the minimal chlorine consumption I am observing (~1 PPM/day with solar cover on, FC never lower than 6 and CYA=80-90), I am quite confident that the pool is algae free. However, the filter pressure continues to increase. Just backwashed again yesterday morning. After adding DE, PSI=10.5. This morning PSI=16.5. Shallow end was used for about an hour yesterday, but other than that, no pool usage for over a week. If the following logic is flawed, someone please explain where and why. If the following logic is not flawed, what else could the filter be catching? I am accustomed to only a few backwashes per season!

    Syllogism #1:
    If the pressure is increasing, the filter is catching something.
    If the filter is catching something, there is something in the water for the filter to catch.
    Therefore, if the pressure is increasing, there is something in the water for the filter to catch.

    Syllogism #2:
    If the pressure is increasing, there is something in the water for the filter to catch.
    If there is something in the water for the filter to catch, the water is not "clear."
    Therefore, if the pressure is increasing, the water is not "clear."
    ~18,000 gal (16x32) vinyl
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    Circupool RJ45 SWG
    Hayward Max-Flo XL SP2305X7 pump (0.75 HP)

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    CJadamec's Avatar
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    Re: one long segment or multiple short segments of pump run time?

    For a CYA of 80-90 your FC of 6 is too low. Your target FC should be around 10. FC/CYA Chart

    You feel confident but your filter is telling you that you are wrong. Just for arguments sake bump your FC levels up to 10-12 for the next week and I bet your pressure rise issues will go away by the end of the week.
    Chuck-
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    Re: one long segment or multiple short segments of pump run time?

    iam, when is the last time you opened your filter to check the condition of the sand or deep cleaned the sand? If a large part of the surface is hard, it is not filtering as designed.
    30000 gal inground vinyl liner;sand filter w/glass media, nuvo uv, TF-100 test kit; 25 years on Baquacil, converted to TFP chlorine in 2016

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    Re: one long segment or multiple short segments of pump run time?

    Quote Originally Posted by CJadamec View Post
    For a CYA of 80-90 your FC of 6 is too low. Your target FC should be around 10. You feel confident but your filter is telling you that you are wrong. Just for arguments sake bump your FC levels up to 10-12 for the next week and I bet your pressure rise issues will go away by the end of the week.FC/CYA Chart
    I have an SWG, so FC target is significantly lower. I will bump up FC level just for argument's sake. Perhaps there is a small amount that is maintaining equilibrium so to speak. I'll just put my SWG at 100% and monitor to make sure FC doesn't get too high. 100% for 24 hours should add over 13 PPM, and FC was 9.5 this morning. With such a high CYA, I'm safe not checking again until tomorrow morning. Meanwhile, I'll keep tracking PSI.
    ~18,000 gal (16x32) vinyl
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    Circupool RJ45 SWG
    Hayward Max-Flo XL SP2305X7 pump (0.75 HP)

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    Re: one long segment or multiple short segments of pump run time?

    You could always supplement the FC with bleach so you don't have to mess with the SWG programing. Are you sure the SWG is maintaining output to hold the pool at a minimum FC of 6 the entire day? You may need to shoot for a slightly high FC if raising your level for a few days clears up the filter problem.

    Sorry I didn't notice that you had a SWG.
    Chuck-
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    Re: one long segment or multiple short segments of pump run time?

    Quote Originally Posted by iam4iam View Post
    Based on the minimal chlorine consumption I am observing (~1 PPM/day with solar cover on, FC never lower than 6 and CYA=80-90), I am quite confident that the pool is algae free. However, the filter pressure continues to increase. Just backwashed again yesterday morning. After adding DE, PSI=10.5. This morning PSI=16.5. Shallow end was used for about an hour yesterday, but other than that, no pool usage for over a week. If the following logic is flawed, someone please explain where and why. If the following logic is not flawed, what else could the filter be catching? I am accustomed to only a few backwashes per season!

    Syllogism #1:
    If the pressure is increasing, the filter is catching something.
    If the filter is catching something, there is something in the water for the filter to catch.
    Therefore, if the pressure is increasing, there is something in the water for the filter to catch.

    Syllogism #2:
    If the pressure is increasing, there is something in the water for the filter to catch.
    If there is something in the water for the filter to catch, the water is not "clear."
    Therefore, if the pressure is increasing, the water is not "clear."
    Have you had rain during that period? When it rains I get runoff into the pool that carries dirt and stuff that the filter picks up. Also stuff falling into the pool from trees around like pollen.

    Sounds like your filter is doing it's job. As someone said, check check the condition of your sand.

    I vote to run your pump for one long period a day. Nothing to be gained by breaking it up. I run my pump 23 hours a day.
    -Allen
    IG 20x50 35,000 gal Cayman Lagoon Hydrazoo plaster w/ spa & waterfall, Pentair Intellichlor SWG, Pentair Mastertemp 400BTU Nat Gas Heater, Pentair FNS Plus 60 DE Filter, Polaris 380 cleaner, Meyco solid winter cover, TF100 Test Kit, Built in 2000 & replastered in 2017

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    Re: one long segment or multiple short segments of pump run time?

    Quote Originally Posted by ajw22 View Post
    Have you had rain during that period? When it rains I get runoff into the pool that carries dirt and stuff that the filter picks up. Also stuff falling into the pool from trees around like pollen.

    Sounds like your filter is doing it's job. As someone said, check check the condition of your sand.
    It has actually rained quite a bit during this time. Quite a reasonable explanation! In fact, the rate of pressure increase had decreased to near 0 during the first 48 hours of pump running. I was waiting for no change in 12 hours, so I left the pump on. The increase in the rate of pressure increase does seem to correspond to the rain. That doesn't rule out the possibility of algae growth "at equilibrium," so I'll still boost FC to eliminate that possibility, but I think debris from the cover (including possible algae there and of course pollen) is a more likely culprit!

    On a side note, the cover is starting to flake and needs to be replaced. I got 2 extras in 2016 @ $25 each!!!! (I should have bought 10, since this one only lasted 2 years, but that is probably because I leave it on all winter instead of the traditional pool closing. Other than more leaf raking and vacuuming in the spring, and shortening the life of the cover, I see no harm in it. I may think twice about continuing that custom if the price of the cover doesn't come back down. Currently at $95. Anyway, that is another discussion entirely.)
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    Re: one long segment or multiple short segments of pump run time?

    Quote Originally Posted by iam4iam View Post
    It has actually rained quite a bit during this time. Quite a reasonable explanation! In fact, the rate of pressure increase had decreased to near 0 during the first 48 hours of pump running. I was waiting for no change in 12 hours, so I left the pump on. The increase in the rate of pressure increase does seem to correspond to the rain. That doesn't rule out the possibility of algae growth "at equilibrium," so I'll still boost FC to eliminate that possibility, but I think debris from the cover (including possible algae there and of course pollen) is a more likely culprit!
    Rainwater will also carry organics into the pool that will increase CL demand. It is the CL and your filter that keeps the pool water clear while the rain tries to mess up your lovely pool.
    -Allen
    IG 20x50 35,000 gal Cayman Lagoon Hydrazoo plaster w/ spa & waterfall, Pentair Intellichlor SWG, Pentair Mastertemp 400BTU Nat Gas Heater, Pentair FNS Plus 60 DE Filter, Polaris 380 cleaner, Meyco solid winter cover, TF100 Test Kit, Built in 2000 & replastered in 2017

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    Re: one long segment or multiple short segments of pump run time?

    FC up to 16.5 this morning. That should take care of what little amount of organics may be present. 24-hour chlorine usage about tripled, but I figure that is due to about triple concentration. (Isn't usage proportional to concentration, e.g. 50% increase in concentration will increase usage by 50%?) Turned off SWG. Only small increase in PSI, but it did rain again, and thunderstorms possible again today. I love May. Will continue to monitor.
    ~18,000 gal (16x32) vinyl
    Hayward sand filter
    Circupool RJ45 SWG
    Hayward Max-Flo XL SP2305X7 pump (0.75 HP)

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    CJadamec's Avatar
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    Re: one long segment or multiple short segments of pump run time?

    If you have your pool covered your chlorine usage is not going to triple just because you have elevated numbers. With your CYA levels chlorine of 16.5 really isn't all that high. You aren't that far out of range for a normal non SWG pool.

    I keep my pool covered all the time and can maintain an FC of 12 which is twice my goal of 6 for a couple days. I typically loose less than 1 FC a day with my pool covered no matter if it rains or is bright and sunny. During the week if nobody is swimming I generally go 2-3 days without having to add any chlorine to my pool.

    If you noticed significant consumption of chlorine when you raised your levels to the point you did you should really consider going thru a SLAM because you have some sort of organic problem. You need to be able to pass an Overnight Chlorine Loss Test which means your pool looses less than 1ppm FC overnight without your SWG running.
    Chuck-
    15x30 AG, Pentair Superflo VS, 19" sand filter, TF-100 test kit
    Aqua Comfort ACT750 heat pump / 6x20 ground mount solar panel / DIY automation

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    iam4iam's Avatar
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    Re: one long segment or multiple short segments of pump run time?

    I think the huge FC loss may have been a combination of higher-than-normal concentration and a bit of organics present. That short "mini-SLAM" was apparently enough to take care of it, though. Water is crystal clear now and OCL last night was 0.
    ~18,000 gal (16x32) vinyl
    Hayward sand filter
    Circupool RJ45 SWG
    Hayward Max-Flo XL SP2305X7 pump (0.75 HP)

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