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Thread: What size of cartridge filter?

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    What size of cartridge filter?

    Hey Guys,

    Complete newbie here, so sorry for the basic questions.

    So I have a DEP51 DE filter which so far has done a reasonable job. Although I now believe the filters will have to be replace, cost wise $190 ish was the cheapest I could find for all 13. My drainage is also blocked, so I have to roll out a hose every time to backwash the system and now the water company is installing a meter. This got me thinking about cartridge filters which I believe might be the more economical option?

    First of all, I have no idea of the physical size I would need, see my signature below for pool specs, any ideas? I was thinking of something along the lines of a Hayward C900, initially that looks like it would be able to handle my pool size? Or should I be looking at something completely different? I had never considered a cartridge filter but reading Pool School it seems like this might be the way to go?

    Thanks for the help guys! Really appreciate it!
    40' x 20' 28k Gal Pebble Tek Free Form Pool
    Sta-Rite DEP51 D.E. Filter
    Sta-Rite PE5E-125L Max-E-Glas
    Sta-Rite PLBC 0.5HP
    Polaris 280

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    duraleigh's Avatar
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    Re: What size of cartridge filter?

    Match the filter size to your pump size. You should find the "pump curve" online or in your documentation and figure how many gallons/minute your pump will produce.

    The best match will be a filter rated about 20% higher in gpm than the pump.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: What size of cartridge filter?

    The PE5EL should be a 1 hp pump, which pumps about 50 gpm.

    There's no such thing as oversizing on a pump but make sure your minimum sq ft is equivalent to your flow rate.
    Sean Assam - Sean@teamhorner.com
    National Accounts and Commercial Products Manager
    AquaCal Heat Pumps www.aquacal.com
    AutoPilot Salt Chlorine Generators www.autopilot.com

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    Re: What size of cartridge filter?

    Hey Guys,

    Thanks for the replies. So this filter sizing and pump sizing has got me all messed up. I figure out that at 50GPM I will need to purchase a much smaller filter, originally I was going with a Hayward 1200 series, however that makes me think I would need a pump capable of 120+ GPM as an ideal match for this unit.

    Since I am looking at replacing my pump also, I guess I just need to throw down the cash and buy both at the same time. I have two goals, one is that I need to switch to a cartridge filter and the other is that I really want to start saving on the electricity bills. So if I go with a larger filter and then a larger pump I will start to save more money due to the fact I won't need to pump for as long?

    Sorry for all of the basic questions, I have been reading far too many posts and now just getting confused!
    40' x 20' 28k Gal Pebble Tek Free Form Pool
    Sta-Rite DEP51 D.E. Filter
    Sta-Rite PE5E-125L Max-E-Glas
    Sta-Rite PLBC 0.5HP
    Polaris 280

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    mas985's Avatar
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    Re: What size of cartridge filter?

    Owning a cartridge filter myself, the best move I made was oversizing the filter. With your size pool, I would go with at least a 420 sq-ft filter and maybe even larger. In that size range, all filters have a 150 GPM limit so flow rate considerations are not all that important. Why so big, you might ask? The larger the filter, the less often you will need to clean the filter.

    I have a 21k g pool with a 420 sqft filter and clean it twice a year but could go once a year if I wanted since there really isn't any PSI rise when I clean it.

    Also, I wouldn't upsize the pump unless you need the extra flow rates. The filter ratings are maximum flow rates and there is no minimum. In fact, the lower the flow rate, the better the filter will work. 1/2 HP should be enough for your setup.
    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: What size of cartridge filter?

    look into a clean and clear 420 or 520. They are my favorites on the market. Dont worry about pump sizing, the larger the cartridge filter the slower the water moves over the element. The slower water passes through the element, the finer the particle filtration becomes. You can get near de particle filtration if you run a low speed pump on an oversized cartridge. Almost all of our ingrounds now get clean and clear 420s and 2 speed wisperflows. We have never had higher customer satisfaction.
    Matthew
    Involved in the pool and spa industry
    Pittsburgh, PA

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    Re: What size of cartridge filter?

    A quick calculation on 28,000 gallons:
    One turnover every 8 hrs = 58.3 gpm
    How many hours per day are you running your pump?

    You should go with the largest cartridge filter you can afford. Longer cycles between cleanings = less work!

    Regarding upsizing your pump, you would want to first consider that you want at least one turnover of your pool volume per day. So with your current pump, you would need to run a little more than 8 hrs/day to "theoretically" filter all your water.

    If your goal is to reduce electrical costs, you need to look into two speed or variable speed pumps and running in low speed for more hours per day. The lower speeds operate much more efficiently (cost-wise) than running a higher horsepowered pump for fewer hours/day. Again, you need to make sure you're getting at least one turnover.

    There a several members here that can share their experience with the variable flow pumps.
    Sean Assam - Sean@teamhorner.com
    National Accounts and Commercial Products Manager
    AquaCal Heat Pumps www.aquacal.com
    AutoPilot Salt Chlorine Generators www.autopilot.com

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    TripleB4me's Avatar
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    Re: What size of cartridge filter?

    My pool is about 26,000 gallons and I have a 300 sq. ft. filter and it does just fine. I have detected zero rise in pressure and I clean it at years end and there is very little to clean out. I also use skimmer socks so I'm sure that has a lot to do with why my filter never gets very dirty.
    20x40 IG Vinyl, 1.5 HP Whisperflo, Sta-Rite System 3 (300) Sq. ft Cart
    Intellichlor IC40 SWCG, 125,000 BTU Pentair heatpump, Polaris 280
    7' IG FG Spa, 2 HP Whisperflo, Pentair Dynamic III Cart (100) Sq. ft

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