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Thread: Whats the best way to know what the pressure should read on my system?

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    sgt173's Avatar
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    Whats the best way to know what the pressure should read on my system?

    I'm putting in my new filter soon that just came the other day.Right now its reading about 16-17 lbs.After I cleaned the old one it was at 13 when I put it back in. Now is getting back up to to what is was when I moved here 2 months ago.
    No one has been using the pool either since it been to cold to keep it heated I've just been adding acid to get it lower and some bleach weekly to keep get inline and running the pump a few hours a day for now until I get my own kit.Due to what the pool store says it is now.
    The old filter was in bad shape I have to admit,so How can the pressure keep going up with only surface dust being filtered out for now?
    I was told by the local pool store the best way to know what it should read is check it with no filter in it first.
    Does this sound right to you guys or should I just put in the new one and go from there from now on??
    Cant wait till my Taylor k2006 test kit gets here so I can learn how to use it.I've only used the two way OTO and PH kits before for my hot tub up north
    and that was easy and I keep the water great with that.
    Thanks for the Forum Guys!! I been reading a lot on it trying to figure out the best way to keep it sparkling clear like it is now without spending a lot.
    6100 gal. In ground pool,1HP Pentair Superflo pump, 100 sq. ft. Cartridge filter , 3" tab dispenser, Aqua-Cal heat pump system ,Baracuda MX8 cleaner, in a Birdcage,Taylor K-2006 complete FAS-DPD chlorine kit.
    "Remember Folks Freedom Isn't FREE !!!"

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    JasonLion's Avatar
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    Re: Whats the best way to know what the pressure should read on my system?

    There is no real way to know what the pressure should be after equipment is replaced without trying it. In principle it can be calculated, but in practice the calculations are difficult and often depend on values that are not known very accurately. That said, I would expect it to be somewhat similar to the old clean pressure, say somewhere between 10 and 15.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Whats the best way to know what the pressure should read on my system?

    so How can the pressure keep going up with only surface dust being filtered out for now?
    It is very possible to catch a lot more than surface dust in your filter....including algae that you can't see. The debris keeps collecting and your pressure goes uI assume your water appears crystal clear, right?

    Can you post a complete set of test results?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    sgt173's Avatar
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    Re: Whats the best way to know what the pressure should read on my system?

    Yes, the water Is really clear and clean and nothing can get past my skimmers but dust and surface floaters maybe.
    The old filter was pretty clogged up and look really bad when I cleaned them best I could with TSP last month all scummed up and calcimined up,but I didnt see any kind of algae that looking so I just ordered a new one.This one is not worth the effort to try and save probably the original one from back in 2010 when the pool was built
    The last test I got run at the pool store here 2-13 2015 .
    TC 5.0
    FC 5.0
    CC 0.0
    pH 8.0
    Acid demand 2
    TA 90
    CH375
    Stabilizer 140
    Total Dissolved Solids 1,100 ppm
    I have added 2 cups of MA a week and 1/2 gallon bleach a the last few weeks in a row and stopped adding any tabs since Ive been here.I think that was why the stabilizer and chlorine so was high?
    My test kit should be here today or tomorrow I can get a better reading to compare them.
    6100 gal. In ground pool,1HP Pentair Superflo pump, 100 sq. ft. Cartridge filter , 3" tab dispenser, Aqua-Cal heat pump system ,Baracuda MX8 cleaner, in a Birdcage,Taylor K-2006 complete FAS-DPD chlorine kit.
    "Remember Folks Freedom Isn't FREE !!!"

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    Re: Whats the best way to know what the pressure should read on my system?

    With an (estimated) CYA of 140 (it could be higher), you are not keeping enough chlorine in the pool to prevent all algae, even though your pool looks clear.

    1. I suggest you read "The ABC's of Pool Water Chemistry" up in Pool School and get a clear working knowledge of the FC/CYA relationship.

    2. Your pH should never be in the 8's.....it should be in the mid 7's. This may have contributed to the calcification on your cartridge.

    Your cartridge is only doing what it is supposed to do......keep your water clean.
    The old filter was pretty clogged up
    With what? My point that I may not be making well is that it surely sounds like you are assuming your cartridge was at fault when the indicators tell me it was your water chemistry. That is most often the case.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Divin Dave's Avatar
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    Re: Whats the best way to know what the pressure should read on my system?

    sgt,
    I might also add that a 100 sq ft filter, although probably 'sufficient' for your size pool, is not oversized at all. When it comes to cartridge filters, the bigger the better!

    This means you will have to clean it often and and any calcification which might occur in the filter will just exasperate the situation. The high PH will really do a number on you if you dont keep it in check.

    Put the new filter in and whatever is your pressure is as good as its gonna get. Then whenever the pressure rises about 20%, its time to clean it.
    Divin Dave,
    IG Vinyl, 15' x 30', 3 1/2' - 6' deep, Oval, ~15K gal, Intelliclor IC40, Intelliflo VS pump, Clean and Clear 420 Filter, auto-fill-disabled, Retrofit LED Color Light, Dolphin Nautilus Robot, TF100 Test Kit, Taylor K1766 Salt Test Kit, Tftestkit Pressure Gauge.
    www.tftestkits.net Experience- it's what's learned just after you needed it most !!

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    sgt173's Avatar
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    Re: Whats the best way to know what the pressure should read on my system?

    Thanks, duraliegh and Dave.Ive been trying to get it down the last few weeks and it did get about 3' of rain last Monday and after I put in the MA I haven't tested it yet was hoping to get my Kit to test myself, BTW it just came a little while ago so I will test it tomorrow when its light outside then add more MA if its not down from the last test.
    Your right about the PH being high and it was high when I got here and started checking it and the filter was really bad meaning a lot of calcification already on it (too hard to clean even with a TSP Soaking) and all the bands broken.So I'm sure it was because they didn't keep the PH in check.They just said they did what the pool store told them to do.I plan on keeping the filters clean and the water in good shape.
    Thanks again
    6100 gal. In ground pool,1HP Pentair Superflo pump, 100 sq. ft. Cartridge filter , 3" tab dispenser, Aqua-Cal heat pump system ,Baracuda MX8 cleaner, in a Birdcage,Taylor K-2006 complete FAS-DPD chlorine kit.
    "Remember Folks Freedom Isn't FREE !!!"

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