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Thread: Sand Filter Troubles (Deep Clean + DE = cloudy pool?)

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    Sand Filter Troubles (Deep Clean + DE = cloudy pool?)

    Hi,
    You guys have all been super helpful with loads of other questions I've had, so I hope someone can help me here, too.

    I recently completed a SLAM (Algae or pollen? (Lots of pictures)) see there for the progress). I added DE to my sand filter following the instructions from pool school. My beginning preassure was 14.5 and I added DE until I got to 15.5, which turned out to be 1.5 cups. I started noticing some strange behavior where my filter would seem to spit out a cloud of dark junk when the pump would start. Given that and seeing more brown junk on the bottom of my pool a few days later I was suspecting more algae, so I vacuumed the bottom, backwashed just in case (my preassure wasn't up high enough but tons of really dark water would come out), and slammed. However, I passed the OCLT (How O need the OCLT be?) the first night, had <0.5 CC, and my water was clear againthe next morning .

    After that I back washed and deep cleaned my filter because I thought the cloud spitting was the result of a channel or something in the send, following the instructions stickied to this section of the forum. I didn't see any channals, the sand level looked fine (I guess), and not much large particles, but when I stuck the hose deep in the filter lots of really fine looking greenish brown debris came up through the center pipe. It looked like the mixed up DE in the bucket, but much darker, or like the fine junk that collects in the bottom of my pool Finally, I put everything back together and added some DE to my sand filter until I got to 15.5 psi again. On the first run the preassure ran up to 18 or so, but I didn't want to backwash too early since I often see warnings not to backwash before pressure gets to 25% up. I had to clean out my skimmer basket though, so I turned of the pump, dumped the leaves and sticks (we had had a storm), and as soon as I turned the pump back on a plume of yellow brown muck shot out the return jet and the pressure fell back to 14.5. There was also some brown stuff on the bottom of my pool, but I had to tend to some renovation projects and didn't have time to vacuum. Of course right then the diaphragm of my auto cleaner had to break, so I just let the filter run. Yesterday I checked the water and it was pretty cloudy (I hadn't added FC since I passed the OCLT during the SLAM. My FC then was 17 at CYA <40
    I found 4.5 FC, 0 CC, PH 7.6.
    Today the water was even more cloudy, and I finally got to vacuum. I got smart to what was happening, so after I vacuumed I turned the filter off, set it to "rinse" and sure enough I got a stream of brown gunk out of my waste hose.

    Here is what I think is happening: The DE ends up clogging up in front of the laterals when under pressure. When the pump stops things settle, but when I turn it back on the DE and all the junk it caught goes through the lateral (because it's a sand, not a DE filter), and comes out the return.
    Today's numbers from after that were FC 3 and PH 7.6, so I added 2 FC worth of chlorige. Still not enough loss on a sunny day to suspect algae, and again, this is after a SLAM that passed OCLT without FC ever dropping below the minimum. The water also was clear, so all that came in was pollen, dead leaves (a tree trunk above my pool died in the spring so I got fall all summer yay!), and the DE

    So, now I guess I have about 1 cup of DE floating in a pool with a sand filter incapable of picking it up. But, something else might be going on. Is there a different explanation for the dirty water coming in the pool when re-starting the pump? Or why else is my filter just catching junk only to release it again on the next pump start.

    My questions are: Is this a case of DE in sand filter straight out failing, and has anyone had that happen before?
    How to fix it? (My best guess is throw in more of the clarifier that I still have sitting around from the previous owner, vacuum it up, backwash, and then clean the filter again.)
    Any other ideas for getting DE out of a sand filter pool, if that is the problem?



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    24' round above ground 52" vinyl pool - 12690 gallons at 45'' fill.
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    Hayward S180T 150lb Sand Filter.

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    Re: Sand Filter Troubles (Deep Clean + DE = cloudy pool?)

    I put DE in my filter once or twice. It never came back out that I know of. Are you sure everything was still in the right place after the deep clean? If you are having filter trouble, clarifier may make it worse. Could you vacuum the debris to waste, thereby bypassing the filter, so you can tell later if more is coming out?
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    Re: Sand Filter Troubles (Deep Clean + DE = cloudy pool?)

    After you backwash, and the sight glass runs clear, are you rinsing until the sight glass runs clear again? That should be 30 seconds minimum to even 2 minutes.

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    Re: Sand Filter Troubles (Deep Clean + DE = cloudy pool?)

    Thanks for the ideas.

    Are you sure everything was still in the right place after the deep clean?
    the lateral did not move, and the behavior of spitting dirty water into the pool happened even before the deep clean.

    If you are having filter trouble, clarifier may make it worse.
    Hiw so? The way I understand clarifier it makes small particles clump together to form bigger stuff. Hence, my thinking is that all the particles too fine to be caught by my laters will actually clump together and get stuck in the filter. That may clog it, but a deep clean would get it all back out.

    What other negative things does clarifier do?


    Could you vacuum the debris to waste, thereby bypassing the filter, so you can tell later if more is coming out?

    i could do that, but how would that help? I don't want to have to vacuum to waste every time I get pollen in my pool. also, I'm really weary of vacuuming to waste in general. I lose so much water backwashing that I have to re-fill the pool almost every time I do. I easily lose about an inch of water in about 4 minutes of backwashing, and it takes me 20-30 minutes to vacuum my pool. That means I's have to re-fill the pool two to three times just during thet process.

    Quote Originally Posted by MarianParoo View Post
    After you backwash, and the sight glass runs clear, are you rinsing until the sight glass runs clear again? That should be 30 seconds minimum to even 2 minutes.
    i do that, yes. But the junk comes out not even after I backwash, but just after I turn the pump off and then back on.
    24' round above ground 52" vinyl pool - 12690 gallons at 45'' fill.
    Hayward Power-Flo Matrix SP1510Z1XEHC (1HP, SP).
    Hayward S180T 150lb Sand Filter.

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    Re: Sand Filter Troubles (Deep Clean + DE = cloudy pool?)

    If you vacuum to waste, you won't need to backwash.
    As for the clarifier, the basis of TFP is to simplify pool care, using the most effective methods. That means not adding unnecessary things, including clarifiers and flocs. (There are times they are needed, but generally aren't recommended.)
    26' X 52" Intex Ultra Frame. Intex Sand Filter
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    Re: Sand Filter Troubles (Deep Clean + DE = cloudy pool?)

    Quote Originally Posted by PAGirl View Post
    If you vacuum to waste, you won't need to backwash.
    As for the clarifier, the basis of TFP is to simplify pool care, using the most effective methods. That means not adding unnecessary things, including clarifiers and flocs. (There are times they are needed, but generally aren't recommended.)
    I understand what vacuum to waste does, and I'm open to trying it, but I don't know how this would solve my problem (Return spews cloudy dark muck on re-start). Id like to understand how and why I'm doing it and how it could solve the problem. That's what inunderstand the TFP philosophy to be about - only do things to your pool understanding how and why. That's why we test our water and measure our chemicals.

    I also understand that TFP method doesn't usually recommend clarifier, but I feel like I got in this mess after following all the TFP recommended steps: 1. SLAM, 2. Clean Filter, 3. Add DE. The result of following all those exactly according to instruction is a cloudy pool. That's why I'm hoping someone here can help me figure out what's wrong and how to fix it. I don't see how repeating any of those steps would fix it since I suspect I have a pool full of suspended DE and pollen (But I'm not sure - maybe something else is going on with my filter). That seems precisely like one of those times when clarifier or flock would help, but I'd like to hear if anyone has a good guess of what's going on before I go there.
    24' round above ground 52" vinyl pool - 12690 gallons at 45'' fill.
    Hayward Power-Flo Matrix SP1510Z1XEHC (1HP, SP).
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    Re: Sand Filter Troubles (Deep Clean + DE = cloudy pool?)

    Are you rinsing after you backwash? If the filter is letting that much debris get past it then something is wrong inside the filter.
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    Re: Sand Filter Troubles (Deep Clean + DE = cloudy pool?)

    Quote Originally Posted by pooldv View Post
    Are you rinsing after you backwash? If the filter is letting that much debris get past it then something is wrong inside the filter.
    Yes, I rinse after I backwash until the water looks clear. But this debris spouting is happening without a backwash. I haven't backwashed since I deep cleaned the filter. Because my pressure isn't rising.

    How would I go about diagnosing what's wrong with the filter?
    24' round above ground 52" vinyl pool - 12690 gallons at 45'' fill.
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    Re: Sand Filter Troubles (Deep Clean + DE = cloudy pool?)

    I agree with pooldv.......something wrong with the filter...........lets back up a step.

    Take your filter apart. Take all of the sand out and put it in a wheel barrow and clean it that way. You can use a shop vac to help get it out. If you need to put the sand on a tarp after you clean it to make room for the rest of the sand.

    With you saying there was all kinds of dark chunks coming out I think it is best to go this route.

    Kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    Re: Sand Filter Troubles (Deep Clean + DE = cloudy pool?)

    Thanks, I'll try to do that today or tomorrow. I heard people using a shop vac to get it out into a wheelbarrow, so I'll try that.

    Once I get it out, what am I looking for?
    24' round above ground 52" vinyl pool - 12690 gallons at 45'' fill.
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    Re: Sand Filter Troubles (Deep Clean + DE = cloudy pool?)

    Deep Cleaning a Sand Filter

    I am sharing this link because it shows you what a sand filter looks like on the inside to give you an idea of what you will find.

    You are going to look to make sure all of the laterals are good-no cracks or broken ribs, no sand pieces stuck in the ribs, upright pipe not chipped or cracked, etc.

    You will also be able to really clean the sand up.

    Now when you go to put the sand back in use care.

    -Put something over the pipe to make sure NO sand does down it.

    -Make sure the pipe is seated.

    -Fill the filter about half way up with water to help cushion the fall of the sand

    -hand place the sand until the laterals are completely covered and then some.

    -run the filter on rinse to get the sand where the filter wants it.

    Good luck and let us know how it goes.

    Kim
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    Re: Sand Filter Troubles (Deep Clean + DE = cloudy pool?)

    Thanks Kim,
    I hadn't had a chance to take it apart yet, and but luckily I haven't seen the dirt spewing in a while. I vacuumed to waste, and now I was just running my pump 24/7 in the hopes of clearing things up. I had one question after reading that article again. It says the openings of the laterals are just small enough so that a grain of sand doesn't pass through. Given that, it would make sense that the DE could just go through all the sand and come right back through the filter. Everything I had seen coming out of the filter was definitely smaller than a grain of salt, so I'm guessing that I may just be dealing with the inefficiency of a sand filter rather than a crack. I'm actually moe curious why something much finer than the sand wouldn't just pass through the whole filter system.

    (What I'm imagining is something like this: Once the DE enters the filter it gets stuck somewhere in the middle, and while the pump is going nothing moves. But, as soon as the pump is turned off the pressure stops and the DE and other small stuff just float suspended mid way in the filter. Once the filter is turned back on th DE makes it the other half way through the filter, goes through the laterals, and goes right back into the pool.)

    I also called Hayward today about the issue (Hadn't seen your reply yet) and got a really stupid answer. The guy said it was normal behavior, don't backwash until your 10psi over standard, and dirt being spewed back in is always a maintenance issue, not an equipment issue ("Go to the pool store!" He said). He also said that if there was anything wrong with the filter water would come out the backwash line. ???? I was too flabbergasted (After a 2 hour hold) and didn't have the nerve to argue with an irritated guy that clearly just wanted 5PM to get there, but if I had water coming it the backwash line that sounds like an issue with the multi port valve, not the filter.
    24' round above ground 52" vinyl pool - 12690 gallons at 45'' fill.
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    Re: Sand Filter Troubles (Deep Clean + DE = cloudy pool?)

    The DE gets "stuck" in the sand. That allows the filter to "polish" the water. The best of both worlds-easy of a sand filter, polish of a DE filter.

    I have never had the DE come out of my filter back into the pool and I use it all of the time. I know just how much my pool likes. It WAS a trial and error kind of thing. Too little and the pressure did not rise so it did not really do anything. Too much and the pressure went up to high to fast. So I did a back wash to remove some of it. It is a balancing act that is worth doing.

    2 HOUR hold for that?? You poor thing! You are correct in what would be wrong if that happened So sad when they do not have the proper training to answer simple questions

    We got ya covered. It might take one of us a little while to answer but at least you will not be stuck with the phone to your ear LOL

    Kim
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    Re: Sand Filter Troubles (Deep Clean + DE = cloudy pool?)

    Well, here is a temporary report.

    I got so discouraged and overwhelmed with the situation and just didn't have time to take my filter apart that I didn't mess with the pool for about a week. Of course that just turned everything green (I always thought "If I got out and test I really should be taking the whole thing apart, and I don't have time to do that right now."

    I've slammed before, and normally it works really quick, but not this time. I've been trying to keep my FC at 16 for three days now and the pool is still incredibly green . These really are the best swimming days of the summer and I'm just ruining it.

    Even if I kill all the algae, I'm afraid my filter will never get the dead stuff out. Anyways, I'll post more updates once the water isn't green, hopefully. Quick question by the way: Given my filter woes, do I really need to SLAM until the water is clear, or can I stop when I pass an OCLT?

    Thanks
    24' round above ground 52" vinyl pool - 12690 gallons at 45'' fill.
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    Re: Sand Filter Troubles (Deep Clean + DE = cloudy pool?)

    I've never used de in my sand filter, seems too messy. I bought a slime bag that fits on a return fitting. It is a1 micron filter bag that will clear your water well after the algae is dead.You do have to wash it with the hose often, but I find it to be very user friendly! If I were in your shoes, I would slam that algae outbreak, and near the end, when the water is white and cloudy, use the slime bag to get back to crystal clear water!
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    Re: Sand Filter Troubles (Deep Clean + DE = cloudy pool?)

    Quote Originally Posted by mulia View Post
    I've never used de in my sand filter, seems too messy. I bought a slime bag that fits on a return fitting. It is a1 micron filter bag that will clear your water well after the algae is dead.You do have to wash it with the hose often, but I find it to be very user friendly! If I were in your shoes, I would slam that algae outbreak, and near the end, when the water is white and cloudy, use the slime bag to get back to crystal clear water!
    That is good advice!
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    Re: Sand Filter Troubles (Deep Clean + DE = cloudy pool?)

    Thanks for the tip with the slime bag. I was searching around for it on the forums and found this helpful thread:

    SlimeBag for 1/10 of the price, yes you can!!
    In there several folks mentioned that they would get debris spewed back into the pool while vacuuming without the bag. So, it looks like the behavior of my filter might not be abnormal after all. If several folks report dirty water shooting back out without the bag, then I can see how my sand filter would do the same.

    I also saw that you can rig the same thing up cheaper with a bag from McMaster (McMaster-Carr) and some home rigged adapter with pieces from the hardware store, Sinai think I'll try to give that a whirl.

    Now I just have to figure out how to loosen my return fittings that I installed with two 18" pipe wrenches before filling the pool :/
    24' round above ground 52" vinyl pool - 12690 gallons at 45'' fill.
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    Post Re: Sand Filter Troubles (Deep Clean + DE = cloudy pool?)

    Alright, here is an update:

    First, the good news: The pool looks clear now.





    And I was able to figure out a way to attach the homemade skum bag. I ended up being able to use a sink drain line piece with a little lip and attach it under the ring that normally holds my eyeball return yet in. I (well, my wife) then sowed up the bag and I clamped it on the pipe:



    This bag is one of the McMaster Bags. Here is the page: McMaster-Carr
    I ended up buying the 1 Micron 100GPM rated one. I couldn't figure out the math for how much GPM my system actually outputs, but that seemed good enough. They don't tell you how much shipping is, and when I just checked my card statement I was a bit miffed to find out that this $6.40 piece ended up being $12.99 with shipping. Oh well, on to the more puzzling parts.

    First: I have often read here that you can't filter out algae, you can only kill it with chlorine. I don't understand this though. After my pool was incredibly green, I kept slamming it for a few days and saw hardly any progress. Eventually I got frustrated and upped the FC to around 21 instead of 16. Two days later my pool looked a lot better, and my filter preassure started going up. Right before I installed this bag I had to backwash the filter. That means the water in the pool looked like the first picture, but what came out of my backwash hose was the greenest algae soup I've ever seen. It really looked like I didn't kill the algae but just cought it in my filter. I didn't take a picture of the water stream, but here is a picture of the deposit left on the ground where my backwash runs:



    That doesn't look like killed algae to me.

    Second: The issue with the dirt being spewed back. I can't use the filter bag while just running the pump because it slows my water down so much that it wouldn't circulate in the pool. Instead, I decided to just use it while vacuuming. This led to three important observations:
    1. Even this 1 micron filter bag allows some brown/green junk to just go through the filter. If this can't catch it, why should I expect my sand filter to be able to handle it? It does, of course, go through the sand filter first anyways before going through the bag. I don't know if you can see it, but here is my trying to take a picture. Note the could of dirt around it, and also, note that all the dirt caught in the filter bag did not get caught by my sand filter:






    2. The bag displays the exact same behavior as my sand filter on starting/stopping. If I vacuum, turn of the pump to clean my skimmer basket, and then turn the pump back on I immediately see a cloud of junk coming out of the filter all the way around. This gives me further reason to think that there is nothing wrong with my filter, but that I just seem to be cursed with a pool that has particles in it smaller than most people experience. I am less inclined than ever to rip open my sand filter and take all the sand out. Thoughts?

    3. My remnant algae WILL NOT DIE . Every day for three days now I've been vacuuming with the bag and with my FC reset to 16 once a day and still I get a green filter bag, and green stuff coming out of the filter. You can see the little dark spots in the second picture - those are small pools of super fine green/brown stuff that pool on the bottom while I'm filtering 24/7. I'm sure it's the stuff that comes right back through the filter because it's so small. I am also not seeing any white dead algae. What is going on? I get that this green stuff settles in the little bumps and creases on the bottom of my pool, but after a week of slamming, shouldn't the chlorine bleach this stuff out? More to the point: I have been using hairnet skimmer socks, and they catch some green stuff. After 24 hours of having chlorinated water rush over it, why is it still green? Isn't SLAM level supposed to kill the algae, and dead algae isn't supposed to be green? Or am I missing something here. I promise there is no way my CYA is over 40. I haven't added any after 4 tests that all got less than 40, and I've since backwashed and vacuumed to waste. HALP!!!
    24' round above ground 52" vinyl pool - 12690 gallons at 45'' fill.
    Hayward Power-Flo Matrix SP1510Z1XEHC (1HP, SP).
    Hayward S180T 150lb Sand Filter.

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    Re: Sand Filter Troubles (Deep Clean + DE = cloudy pool?)

    It takes time to kill algae and it takes even longer to filter it out using a sand filter. Yes, your filter will catch both dead and live algae. However, you can't just use the filter to get rid of algae and because it multiplies faster than your filter can filter it out. The purpose of a SLAM is to increase FC back to SLAM levels several times a day so that you can kill it faster than it can reproduce. It is also important to brush at least once a day because algae forms a bio shield which protects it from the FC and brushing removes the bio shield exposing it to the FC.

    Sand filters take the longest to clear out the dead algae because they can only filter down to 30 microns. My DE filter can clear a swamp in 3 days and it can filter down to 3 to 5 microns. You can add DE to a sand filter to help speed up the process. Read this tutorial: Pool School - Add DE to a Sand Filter

    It would hurt to open up the filter, make sure that your sand hasn't channeled, do a deep clean and make sure that nothing is broken and that the laterals are in place. Deep Cleaning a Sand Filter
    Karen
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    Re: Sand Filter Troubles (Deep Clean + DE = cloudy pool?)

    Thanks kcindc - About DE and cleaning the filter, please have a look at my initial post. I did both right before my pool started getting cloudy. In regards to brushing: I have one of those vacuum attachments with brush bristles, so I vacuum the whole pool with that once a day. Let me know what you think, given the initial post and this update.

    Thank you!
    24' round above ground 52" vinyl pool - 12690 gallons at 45'' fill.
    Hayward Power-Flo Matrix SP1510Z1XEHC (1HP, SP).
    Hayward S180T 150lb Sand Filter.

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