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Thread: Backwashing

  1. Back To Top    #1

    Join Date
    Apr 2016
    Houston, TX


    Pentair FN Plus filter, how much of the filter debris do you think it removed on a routine backwashing? Also how many times switching from backwashing to rinse is required?
    15000 Gallon, Taylor K-2005 Test Kit, DE Pentair filter.

  2. Back To Top    #2
    Mod Squad Jimrahbe's Avatar
    Join Date
    Jul 2014
    Bedford, TX

    Re: Backwashing


    My guess is only about 75% of the junk gets eliminated when you backwash. That is exactly why I never backwash my DE filters. I disassemble and clean them twice a year, once in the spring and once in the fall.

    I can do this because those pools have variable speed pumps running at a pretty low RPMs most of the time. Not sure what type of pump you have as I don't see it in your signature.

    Thanks for posting,

    Jim R.
    Finished in 2015 - 17K Gal, IG, 20' x 25' Almost Rectangular Pool, Pebble finish, three rockport water falls. Pentair Equipment: EasyTouch 4, IC40 SWG, 3 HP VS Pump, CCP520 Cartridge Filter.
    TF100 with SpeedStir and SampleSizer, ColorQ Pro 7, Dolphin Premier Robot Cleaner, added Screen Logic 2, added small 3 person Caldera Spa.

  3. Back To Top    #3

    Join Date
    Apr 2016
    Houston, TX

    Re: Backwashing

    Single speed pump. I was told buy the local pool store to backwash when my psi doubles, its normally 10psi when it hits 20 Ill backwash. I'll break the filters down 2-3 times a year for a good cleaning and inspection.
    15000 Gallon, Taylor K-2005 Test Kit, DE Pentair filter.

  4. Back To Top    #4
    Mod Squad YippeeSkippy's Avatar
    Join Date
    Jan 2012
    'burbs of Augusta, Georgia

    Re: Backwashing

    Thats too high to wait to backwash.

    We recommend backwashing when the filter pressure goes 20-25% higher than baseline.

    Maddie :) 12K Fiberglass IG, Infinity 4000 automatic cover, SWCG, Hayward Sand Filter, Hayward 1.5 Pump, Doheny Discovery Robot, Savi Melody LED pool lights, outdoor speakers and other assorted doo-dads. Sundance Altamar Hot Tub.
    Skippy's Pool Cooler --> Skippy's New Fountain Our Build --> Our Pool Solved Our Sloping Yard

  5. Back To Top    #5

    Join Date
    Jul 2012
    Dallas, TX

    Re: Backwashing


    I posted in another thread (post #10) about this recently. It's about my DE Backwashing & maint experiences with my pool.

    is there a consensus?

    I have a Multiport Valve in my pool equipment and I usually Backwash with the following method:

    - Backwash position. Run pump for a few seconds until Sight Glass begins to clear.

    - Rinse position for ~10 seconds.

    I repeat these 2 cycles 10 times. After 10 cycles, I see virtually no DE present in the Sight Glass.

    I don't know the % of old DE & debris/particulate removal with this method, but I track my PSI readings and since the last time I pulled my DE Grids for cleaning in Sept 2013, I haven't accumulated much PSI rise (the amount of 'best-case' starting PSI to PSI after reloading with new DE). My PSI rise has been about 1-2 PSI since Sept '13.

    I load new DE using the "80% rule", by reducing the new DE amount by 1 DE measuring scoop. As an example, my DE Filter calls for 3.6 Lb DE (seven .5lb DE scoops), so I only load that amount after cleaning or installing my spare Grid Assembly. All subsequent DE loads are done with six .5lb scoops.

    I also monitor my flow GPM with a FlowvisŪ Flow Meter to provide an additional measuring tool with my PSI Gauge to let me know when a Backwash is required for my pool.

    I don't use the 25% method but am aware it's the forum recommended procedure and am not disputing that recommendation.

    I'm just passing along my DE pool filter experiences since I switched to the TFP pool water method in June 2014.

    The effect of the basic TFP methodology (FC/CYA ratio & Bleach dosing) has been amazing to say the least, resulting in consistent crystal clear pool water & I haven't 'shocked' my pool since that date, and since adopting the method, my Backwashing frequency (& pulling the Grids for cleaning) has decreased significantly.

    I average ~3-6 months between Backwash cycles. Here's my Backwash dates since switching to TFP dosing in June 2014:


    Based on my pool's DE Backwashing & filtering experiences, I haven't seen the need to pull the Grid Assembly for seasonal or timed-based cleaning. If I was seeing indications of that required, I wouldn't hesitate to perform that maintenance as I have a spare complete Grid Assembly (with Manifold & base assembled) for a fast swap for troubleshooting or cleaning.
    - Pool Type: 15k Gal Gunite IG non-SWG / Built 1988
    - Pump: Pentair Challenger / Sweep Pump: Letro Model LA01N .75HP Single-speed / 6 hrs-day (1 turnover)
    - D.E. Filter: OEM: Nautilus (Pentair) #NS 36 / 36 Sq Ft / D.E. Charge: 3.6 Lb
    - Pentair 4-wheel Sweep LL505G - Booster Pump runs ~2 hrs/day

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