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Thread: 2 speed pump and DE filter

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    2 speed pump and DE filter

    Just a quick (hopefully) question.

    We've recently gotten a 2-speed pump (1.5/.75hp) and I've been running it on low most of the time and then boosting it when I need my polaris 360 to do some work for me for a couple of hours a day. What's weird is that I've been noticing the pressure jumping up faster than just running it on high, like my old pump.

    Yes, I understand the extra pressure from going to the 1.5hp is going to boost the pressure inside the DE filter, what I'm wondering is it hurting the DE filter by running it on low so much, maybe not getting enough pressure on the grids, the DE dropping off the grids and creating extra pressure when I switch to high? Should I just run it on high 8/10 hours a day vs. 18/22 on low and 2/4 hours on high?

    Hope this makes sense.

    Thanks ahead of time for anyone's assistance.
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    Re: 2 speed pump and DE filter

    Uwimage, it's my understanding that the lower pressure is allowing you to capture more fine debris by not pushing the water trough the media as quickly/ hard. Have you noticed any change in the water's look/ clarity? (with a DE filter it might be something only noticeable at night with the pool light on) I don't think the lower pressure would allow the DE to fall off the grids, maybe the longer run time is allowing you to filter more of the fine debris than you used to.

    I also can't rule out coincidence - when you got the new pump maybe it was just time for the grids to get a chemical cleaning If you've the time and inclination, maybe ripping the filter apart will provide a little more insight as to the cause.

    I hope you can get this figured out and have a Trouble Free experience with the new pump Thanks for the kind words on my return

    Ted
    Luv& Luk
    -Ted

    Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

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    Re: 2 speed pump and DE filter

    Thanks Ted,

    I've also made the mistake of hiring a pool company to take care of my pool (yes, I know...a big no, no on TFP) but lack of time and well, lack of time, I tried...they are being fired tomorrow after their last paid for visit. I'm probably a lot more like most of the users here and just don't trust someone to do what I know I can do. (speaking of that...getting a lot of Mule Team 20 in the next couple of days, with a little acid )

    I feel comfortable 'ripping apart' my filter, I'm going to check it Thursday or Friday, when I get some time away from my crackberry and VPN........can't wait to turn it off for a few days!

    As for the runtime, it's weird, as soon as I put it back on full speed it jumps about 3 to 4 psi from the previous time I had it at full speed; maybe I just need to schedule it on high and let it go. I feel by adding a new pump I'm already saving, our old one was over 10 years old so I'm sure the new one is more energy efficient.

    After my next experiment I'll re-post the results in the event it helps someone else!
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    Re: 2 speed pump and DE filter

    Just in case anyone was curious I wouldn't recommend a 2 speed pump with a DE filter.

    I was running the low speed about 18 hours a day and the high about 2 to 3 hours a day for the polaris. After a couple of weeks of doing this I had to back wash twice based on the pressure in the valve...there i sno other reason I can see why this would have happened, its been pretty dry, only a little rain, pool color has been great, numbers all come out fine but I don't want to have to backwash weekly, so I'm back to 8 to 10 hours on high. guess if I ever get a different type of filter I can start using the low speed.

    Hope this helps save someone from buying a 2 speed pump with a DE filter.
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    Re: 2 speed pump and DE filter

    As waste pointed out earlier, it could be that the filter works better at low speed so it is filter more which then requires cleaning more often. I would think that this would be a good thing. A larger DE filter would allow you to go longer between cleanings so I'm not sure I would recommend against a two speed pump because of what you are experiencing only that you should pair it with a large filter which is not a bad idea under any situation.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
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    Re: 2 speed pump and DE filter

    Quote Originally Posted by mas985
    As waste pointed out earlier, it could be that the filter works better at low speed so it is filter more which then requires cleaning more often. I would think that this would be a good thing. A larger DE filter would allow you to go longer between cleanings so I'm not sure I would recommend against a two speed pump because of what you are experiencing only that you should pair it with a large filter which is not a bad idea under any situation.
    Well, I have a 48 sq. ft. Pentair DE Filter, maybe it was the pool stores idea to sell me a Polaris 280 and pump by selling me the 2-speed? Since I have a 360 that needs the extra HP from a pump? Either way, I'm a little upset they didn't say anything about the DE filter and the 2-speed pump; up until now I've been very happy with them, the owner has been very honest and up-front about everything...I plan on calling him on it to see what he says...

    but as an END USER I wouldn't recommend someone with a Polaris 360, DE filter to get a 2 speed pump, sure a .75 HP pump might be fine with a pool with a seperate or no cleaner but with my set up it doesn't work...
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    mas985's Avatar
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    Re: 2 speed pump and DE filter

    Maximum flow rate on a 48 sqft DE filter is about 96 GPM and the optimum flow rate is 72 GPM so my guess is that your 1.5 HP pump is probably producing flow rates close to the filter maximum and it is not surprising that the filter does not clean as well on high speed as low speed. Also, the reason you are backwashing it so often is that it is undersized for your pool's debris load.

    I think that the pool store made two mistakes, first you probably didn't need that big a pump to run the cleaner (on high speed). You can't really run cleaners on low speed of any size pump except maybe a 3HP. Second, the filter is too small for that size pump and for your pool's cleaning load.

    Also note that low speed of a 1.5 HP pump is closer to 3/16 HP which is why it is not powerful enough to run the cleaner on low speed. 3/4 HP on low speed would require a 6 HP pump .

    The cleaner would probably work fine on a 3/4 HP single speed and would also put the flow rate near the filter's optimum. However, that would not solve your frequent backwash problem. That requires a larger filter.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: 2 speed pump and DE filter

    uwimage, do you have a feel for what is clogging the filter so often? Do you have any CC? Get a lot of dust or pollen in the pool?

    We had tons of pollen this year, and I had to break down my pentair 36 sq' a few times more than usual until it subsided, now it's smooth sailing.

    I wonder if you tried using skimmer socks if it would help...

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    Re: 2 speed pump and DE filter

    Just in case anyone was curious I wouldn't recommend a 2 speed pump with a DE filter.
    I don't agree with the above statement.
    I have had a 2HP 2 speed pump with a 48ft2 DE filter for 6 years and use a booster pump pool cleaner. I have no problems at all running the pump on low all the time even when the booster pump is on. The only time I use high speed is when I open the pool and it's cruddy or when I backflush and recharge the DE.
    ~Megan

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    Re: 2 speed pump and DE filter

    Quote Originally Posted by Rangeball
    uwimage, do you have a feel for what is clogging the filter so often? Do you have any CC? Get a lot of dust or pollen in the pool?

    We had tons of pollen this year, and I had to break down my pentair 36 sq' a few times more than usual until it subsided, now it's smooth sailing.

    I wonder if you tried using skimmer socks if it would help...
    It seems that this year is a very high pollen year, lots of our customers are complaining about the excessive pollen this year (these are folks who've owned their pools for 3+ years)
    Luv& Luk
    -Ted

    Having done construction and service for 4 pool companies in 4 states starting in 1988, what I know about pools could fill a couple of books - what I don't know could fill a couple of libraries :-D

    POOL SCHOOL, TF Testkits, Jason's Pool Calculator, CYA vs. cl chart, (Just a few DARNED handy links!)

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    Re: 2 speed pump and DE filter

    Quote Originally Posted by MarkC
    Just in case anyone was curious I wouldn't recommend a 2 speed pump with a DE filter.
    I don't agree with the above statement.
    I have had a 2HP 2 speed pump with a 48ft2 DE filter for 6 years and use a booster pump pool cleaner. I have no problems at all running the pump on low all the time even when the booster pump is on. The only time I use high speed is when I open the pool and it's cruddy or when I backflush and recharge the DE.

    Mark, do you mean you would or would not recommend a 2 spd with DE?

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    tcat's Avatar
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    Re: 2 speed pump and DE filter

    Came across this OLD thread. Seems to be a debate here about 2 speed pumps and DE filters, not really resolved. I'm about to charge my DE filter (undecided on fiber or DE), but curious if it's better to add it while on low (slow steady flow), or high (all at once). IMO on low it might disperse better. Thinking add on low, then run on high for 10 minutes to get it "set". My plan is to just run on low 12 hours/day. (1hp/.13hp, 48' filter)
    IG pebble, 15,000 gallon
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    Mod Squad jblizzle's Avatar
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    Re: 2 speed pump and DE filter

    I guess I would think (and do) the opposite ... that running on high would give a better distribution of the DE on the grids when adding it.

    The water/DE enters at the bottom of the filter, if the flow is too slow, I would think the DE may end up mostly on the lower part of the grids.
    Jason, TFP Moderator
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    tcat's Avatar
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    Re: 2 speed pump and DE filter

    Thanks... I did add (decided on the Zeofiber I had left) on high. Pressure went from 17 to 18 (or pretty much stayed on 18). I notice a thin film of fiber on top of the surface in a few areas, not sure if it was from some backing out of skimmer while adding or running through filter before coated. I assume will eventually get filtered out.
    IG pebble, 15,000 gallon
    48 PentAir DE Filter with backwash valve
    PentAir Whisperflo pump with 1hp 2-speed motor
    Aquabot 4WD, Poolskim
    Intermatic Dual Timeclock with freezeguard
    DIY chlorine feed
    BBB

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