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Thread: Question about adding D.E. to a sand filter....

  1. Back To Top    #1
    Beens's Avatar
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    Question about adding D.E. to a sand filter....

    I've read about adding D.E. to my filter to help filter out the fine stuff that my sand filter doesn't want to get and if I remember correctly it says to do 1/4 cup at a time, mixed with water, slowly poured into the skimmer. Wait a little while then add another 1/4 cup at a time until pressure rises by 1psi.

    Here's my problem. 1/4 cup pretty much does it. Everything says it should be more but if I even do another 1/4 cup I get over 1psi rise.

    Is there any way that 1/4 cup of D.E. added to the filter will even do anything? It doesn't seem like that would be enough to do anything yet adding more causes more than 1 psi pressure rise.

    I keep passing the OCLT, I have clear water and a CC of 0. yet I have this "stuff" that gathers on the bottom of the pool usually in the 1/3 of the pool that is across from my return and you can tell that it forms "behind" the high points in the floor where there is not as much circulation. Right now it's forming a lovely layer on the rest of the bottom of the pool that is only obvious when I brush it up and it leaves a clean floor behind. I am so sick of it.

    I even raised my FC to 15 the other day, kept it there and it maintained and passed OCLT the next morning. (My cya is around 40)

    I'm really over this stupid stuff. I keep thinking it's algae but clear water, passing OCLT and never CC more than .5.

    What the heck?

    FC hasn't gone below 5.5 and I've been aiming for around 9 to hopefully keep it from going under 7.
    CC 0
    PH 7.3-7.4 (definitely not as pink as 7.5) *EDIT* I just ran a ph test and it's actually looking to be between 7.5 and 7.8. Definitely not as pink as 7.8
    CYA 40

    *sigh*

    it's ugly.
    18' x 48" (42" water depth) Intex Metal Frame 6,700 Gallons
    Hayward Power-Flo LX 1.0 HP pump
    Hayward Pro Series S166T Sand Filter
    Original Intex Floating Skimmer

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    JasonLion's Avatar
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    Re: Question about adding D.E. to a sand filter....

    1/4 cup of DE is about right for a smaller filter like yours.
    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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    Butterfly's Avatar
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    Re: Question about adding D.E. to a sand filter....

    Have you cleaned the sand filter? Sounds like the sand could be channeled.

    my-sand-is-channeled-how-to-fix-it-t7626.html
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    You're done SLAMing when:
    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

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    Re: Question about adding D.E. to a sand filter....

    If the "stuff" brushes up into a brownish-greenish-yellowish cloud and then reappears the next day, you can suspect it is dead algae.

    So, despite the numbers, the way to get rid of algae completely is to SLAM the pool.

    Having debris appear on the pool floor is not what we think of as sparkling water so that fails the endpoint of the SLAM.

    1. Your pool water is sparkling (with no debris.....I just added that )
    2. Your CC's are .5ppm or less
    3. You can hold your FC overnight without losing more than 1ppm.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Beens's Avatar
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    Re: Question about adding D.E. to a sand filter....

    Well poop. So dead algae on the bottom = not clear. It sure seems hopeless. I am going to sound like a whiner now but darnit. I don't know if I can do a SLAM now! First of all I guess I'd have to order refills for my chlorine test because I'd need so darn much. I could start now and pray I don't run out but I, well, I'm about to give up.

    I can't go out there in the dark. We have these ridiculous spiders that make huge webs after dark and take them down sometime in the AM and unless I can drag my husband out there with me I am pretty much terrified of walking into one of these huge spiders/webs. I wouldn't be able to check the FC overnight except at dusk and maybe not until 12:30 when I get home from work.

    Plus I've lost faith in my filter. I have to keep it at shock level until it finishes filtering? That could be forever. I'm feeling hopeless and thinking if this is what it takes maybe no more pool. What a stupid way to feel but maybe I'll just give up and learn to love the lovely brownish floor layer.

    BTW yes, it does brush up into a brownish-yellowish-greenish cloud. Plus, whoever decided to put all those seams in the pool should be shot. Algae loves those seams but I've found a brush I can brush them with and I do regularly. (of course it's a little hand scrub brush and I have to hold it in my toes to do it but it works and it's precise)

    *sigh*
    18' x 48" (42" water depth) Intex Metal Frame 6,700 Gallons
    Hayward Power-Flo LX 1.0 HP pump
    Hayward Pro Series S166T Sand Filter
    Original Intex Floating Skimmer

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    Beens's Avatar
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    Re: Question about adding D.E. to a sand filter....

    Here's a pic attempt...

    *edit* gee thanks for uploading them all sideways...
    Attached Images Attached Images
    18' x 48" (42" water depth) Intex Metal Frame 6,700 Gallons
    Hayward Power-Flo LX 1.0 HP pump
    Hayward Pro Series S166T Sand Filter
    Original Intex Floating Skimmer

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    Re: Question about adding D.E. to a sand filter....

    Finished vacuuming. Thank God it's pretty again. Really helps my mood. Of course it will probably be the same yuckiness tomorrow.

    Fyi, pump clean pressure is 10psi. It was just a bit over 10 when I added my 1/4 cup D.E. which brought it to 12. After vacuuming I'm at 16psi. Time to backwash. Then I'll add 1/4 cup D.E. again, test the fc and I guess raise it to shock level.

    Pool calculator says 16 (edit..no it says 15) for cya 40. Should I be maintaining it at something higher than that?

    It's hard to tell with no sun but I feel like I can't call that clear anymore.
    Attached Images Attached Images
    18' x 48" (42" water depth) Intex Metal Frame 6,700 Gallons
    Hayward Power-Flo LX 1.0 HP pump
    Hayward Pro Series S166T Sand Filter
    Original Intex Floating Skimmer

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    Re: Question about adding D.E. to a sand filter....

    Grrr. My husband was power washing the house which tripped the cgfi which means no pump til that lets me reset it.

    Guess I'll add the de and raise the fc after lunch. ..
    18' x 48" (42" water depth) Intex Metal Frame 6,700 Gallons
    Hayward Power-Flo LX 1.0 HP pump
    Hayward Pro Series S166T Sand Filter
    Original Intex Floating Skimmer

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    Re: Question about adding D.E. to a sand filter....

    Well it's just after 715 pm. I just added 121oz of 8.25% bleach which according to the calculator should raise my FC from 8 to 20. A thunderstorm and lunch kept me from doing it earlier. I'm not sure if I should be using the D.E. at this point so I skipped it for now. I brushed around the bottom of the pool for good measure and to make sure the bleach got mixed in quickly. (there wasn't anything accumulating down there yet)

    I am attempting to keep it above 15 ( I hope this is the correct number) so I picked 20 knowing I have not been losing any over night. It should be safe to say I'm starting out at 20 tomorrow morning and hopefully that gives me enough play for checking it between 1230pm and 1pm. I didn't lose very much during the day today so hopefully morning-early noon sun won't burn off more than 5 ppm.

    Wouldn't mind a little assurance. I know I'm burning up this thread with my own replies and pictures. I'm trying not to give up here and hoping I'm going in the right direction.

    Thank you all for your help so far...

    BTW as soon as I can get the time and the nerve to try it, I'm going to check the filter just in case I have any channeling or yucky sand issues. It is only 1 year old so it doesn't seem like there should be problems...but who knows?
    18' x 48" (42" water depth) Intex Metal Frame 6,700 Gallons
    Hayward Power-Flo LX 1.0 HP pump
    Hayward Pro Series S166T Sand Filter
    Original Intex Floating Skimmer

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    Re: Question about adding D.E. to a sand filter....

    Here's an update although it seems like no one is looking at this. Anyway...I hope I'm doing "ok".

    Forgot about lunch with my husband so even though I got out of work at 12 I didn't get home to test the water until 1:45.

    Good news is that it tested at FC 15 so raising it to 20 last night got me through.

    I added 30oz 8.25% bleach again to bring it back up to 20 and after fishing out those annoying little ball things that the stupid pear tree keeps throwing in the pool, I brushed the whole thing again.

    Still had that yucky layer on the whole bottom with the bigger spots on the side farthest from the return. It looked a little better than yesterday but I'm figuring that's only because I vacuumed it yesterday.

    I plan on checking it later and adding what I need to bring it to 20 again because I'm working til noon again tomorrow and it seemed to work today...

    Next stop, Target. I need more bleach.

    Am I doing the right thing?
    Anyone?
    18' x 48" (42" water depth) Intex Metal Frame 6,700 Gallons
    Hayward Power-Flo LX 1.0 HP pump
    Hayward Pro Series S166T Sand Filter
    Original Intex Floating Skimmer

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    Mod Squad Bama Rambler's Avatar
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    Re: Question about adding D.E. to a sand filter....

    We're watching and keeping track. You're doing good. A lot of times we're so busy that we'll check a thread and if there's nothing going wrong we'll pass it meaning to come back later, and of course, things always get busy and we forget?

    If you were doing somthing wrong or there was something we could suggest that you could do better, we would be all over it!
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
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    Re: Question about adding D.E. to a sand filter....

    Aaaahhhh Thank You! That makes me feel better! So no news is good news. lol

    BTW I just ordered my refills of R-0870 and R-0871. Trusting USPS to get it here quick since I could drive to NC to pick it up in less than 4 hours...

    I just accepted that I'm not going in the pool today since it's at FC 20 which is higher than my shock level. Anyway, the sky is always watching and the second I get in the pool the sun goes away and the thunder starts. So today I figured I wouldn't even try. Of course that mean's we won't have a thunderstorm now...
    18' x 48" (42" water depth) Intex Metal Frame 6,700 Gallons
    Hayward Power-Flo LX 1.0 HP pump
    Hayward Pro Series S166T Sand Filter
    Original Intex Floating Skimmer

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    Mod Squad Bama Rambler's Avatar
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    Re: Question about adding D.E. to a sand filter....

    If you're that close to NC you may have it in a day. Two at most. Of course, that's like you're going in the pool. As soon as I say that they'll hiccup and it'll take a week for it to get there.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
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    Re: Question about adding D.E. to a sand filter....

    I ordered my TF-100 on a Tuesday around 1130 am and received it Wednesday afternoon but I paid for UPS on that one. I figure it should be here by Wednesday with USPS and they'll actually deliver it earlier in the day! I must be at the end of the UPS driver's route because whenever I order UPS it comes after 5pm closer to 7pm.

    FedEx is always early and USPS is here between 2-3pm

    I think I can stretch till then since I don't have to test 100 times a day. Here's hoping!

    As a side note, I ought to post a pic of my pool when I first started this year. It was dark green disgusting! :-\
    18' x 48" (42" water depth) Intex Metal Frame 6,700 Gallons
    Hayward Power-Flo LX 1.0 HP pump
    Hayward Pro Series S166T Sand Filter
    Original Intex Floating Skimmer

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    Mod Squad Bama Rambler's Avatar
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    Re: Question about adding D.E. to a sand filter....

    Have you figured out if your filter is bypassing stuff for sure?
    If not then take a sock and tie over the return and then vacuum a little. If the filter is bypassing stuff the sock will catch some pretty large stuff. If it is then you may want to check the sand for channeling as BF mentioned earlier.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
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    Re: Question about adding D.E. to a sand filter....

    Come to think of it I have actually already done that. I have some skimmer socks and I screwed one into my return a couple of vacuums ago. Just some very fine "scum". I forgot about that.

    So I guess the filter is doing its thing...but I still have the mystery stuff.
    18' x 48" (42" water depth) Intex Metal Frame 6,700 Gallons
    Hayward Power-Flo LX 1.0 HP pump
    Hayward Pro Series S166T Sand Filter
    Original Intex Floating Skimmer

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    Re: Question about adding D.E. to a sand filter....

    Tuesday 12:45pm update....

    FC 16
    CC 0
    I added 40 oz to bring it back up to 20. Seems to be working for my schedule.

    I brushed the whole thing again. A little better but still that stupid cloudy film that shows enough that I can tell where I have brushed and where I haven't.

    I decided to add 1/4 cup of D.E. and I took the skimmer hose off so it's just pulling from the intake in the wall. I can't tell if it looks better. At first I thought it might be clearer (although I never thought it wasn't clear in the first place) but it was sunny and it always looks nicer in the sun. I feel like it's a little hazy.

    A couple questions... the 1/4 cup seems to have raised my psi by closer to 2 than 1. Is that ok? (Pleeeasseee say yes!)

    Also, I know that it is safe to swim up to my shock level which is 15 according to pool calculator and 16 according to cya chart.

    But...

    If I have it up at 20 is it an absolute no-no to swim? I remember seeing a spreadsheet type chart around here somewhere that showed the different danger at different levels of cya/fc and if I remember correctly the first "danger" was just with bleaching/damage to swimsuits. I have an old swimsuit I usually wear in the pool and I don't really care about it. It's finally nice and hot out again and I'd love to float around for a little while! I can't find that spreadsheet thing...

    I'll just wait and see if anyone has any input on that....
    18' x 48" (42" water depth) Intex Metal Frame 6,700 Gallons
    Hayward Power-Flo LX 1.0 HP pump
    Hayward Pro Series S166T Sand Filter
    Original Intex Floating Skimmer

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    Re: Question about adding D.E. to a sand filter....

    Wednesday Update..(starting with Tues. PM test)

    Tues. 8:40pm

    FC 16.5 - Add 40oz to bring back to 20

    Wednesday 1:30pm

    FC 16.5 - Add 40oz to bring back to 20 (noticing a trend here?)

    So, some good news today I think. It looks clearer! More sparkly! There is a lot of sun today so I don't know if that's why it looks better but I think it looked better when the sun was behind the clouds too.

    I bought myself a new toy at lowe's yesterday. A new brush! The one I had wasn't great and flopped all over the place. I was killing myself trying to use it.

    The "stuff" really wasn't showing on the bottom today! No clumps/settled spots but when I used the new brush there was still a slight cloud so it's still there. I wonder how many more days? I'm keeping the D.E. in the filter.

    So, no one answered my question about swimming in 20 FC. I really want to go in there today. Even though it's cooler out the water feels really nice! I might just take the risk.

    D.E. question, I am supposed to backwash the filter when the pressure rises 25% for me, normal pressure is 10, so around 12-13 I would backwash. Usually that's after I vacuum.

    When I added the 1/4 cup of D.E. the pressure went up to just under 12. Does that mean I backwash when it goes 25% over 12 now and count the D.E. rise as my "new" clean pressure?

    I'm adding a couple of pics from today in case anyone cares....
    Attached Images Attached Images
    18' x 48" (42" water depth) Intex Metal Frame 6,700 Gallons
    Hayward Power-Flo LX 1.0 HP pump
    Hayward Pro Series S166T Sand Filter
    Original Intex Floating Skimmer

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    Butterfly's Avatar
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    Re: Question about adding D.E. to a sand filter....

    So, no one answered my question about swimming in 20 FC. I really want to go in there today. Even though it's cooler out the water feels really nice! I might just take the risk.
    You can swim safely between min and shock level based on your CYA, assuming the pool is clear enough to see someone on the bottom, and yours is much clearer than that.

    I would use the clean pressure psi at first clean, prior to adding DE. I assume you will add only half as much DE next time.

    You are making good progress
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    You're done SLAMing when:
    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

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  20. Back To Top    #20
    Beens's Avatar
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    Re: Question about adding D.E. to a sand filter....

    Well I went in the pool even though it was FC 20 and my shock level is 15-16. I didn't melt... I know it's not recommended....but I'm bad.

    With the D.E. is 1/8 cup even going to do anything? Seems like such a small amount that it wouldn't make any difference.

    And you're saying to still backwash at 12? (Clean pressure with no D.E. is 10)

    That means I'm going to have to backwash again really soon.
    18' x 48" (42" water depth) Intex Metal Frame 6,700 Gallons
    Hayward Power-Flo LX 1.0 HP pump
    Hayward Pro Series S166T Sand Filter
    Original Intex Floating Skimmer

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