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Thread: Pool still very cloudy

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    Pool still very cloudy

    OK - I have been reading this forum for about 3 years now and have learned a lot, but apparently I still have much more to learn. I started using the BBB method 2 years ago with great results, and I have had crystal clear water after usually only a couple of days, using a modified SLAM method (just threw in about 5 gallons of Sodium Hypochlorite 12.5% after opening and voila - about 3 days and a few dozen vacuuming sessions and worm retrieval sessions later the pool was clear; then I would correct the other chemistry as needed).

    We have had this pool, an 18'x36' 22,468 gallon pool for about 12 years now, and one way or another things would work out. But after reading here I now realize I used way too much chlorine (so far no noticeable ill effects), but I know my ph was off and I have lots of small wrinkles on the bottom of the deep end and a few small ones in the shallow end. Those will have to wait until I replace the liner, which I estimate to be in about 2-3 years, just to be safe.

    Anyway, back to this years problem. I live in upstate NY, and we have had a safety winter cover for about 3 years. This resulted in a much greener pool than we were used to when we opened it, and also much dirtier (sand and grit) because of the porous nature of this type of cover. But it is easy to take off and looks nice and keeps the grandkids safe when they visit, so I live with it. This year we had a few very warm days in late April/early May, and I didn't get the cover off until last Wednesday. It was very green.

    So I poured in my first 4 gallons of "chlorine" (my name for the NaClO 12.5%) left over from last fall. And the pool went from green to cloudy turquoise - so cloudy I could not see the bottom of the deep end. I put DE in the filter and started vacuuming using the hose that goes into the skimmer and through the pool circulation flow. After 2 more days and about 5 more gallons of fresh "chlorine" the pool was still very cloudy but was slightly better. So at this point I did another backflush/DE recharge cycle and started vacuuming with the robotic vacuum (Hayward AquaVac). This uses internal reusable filters to clean the pool. The first day I forgot to put in the donut over the main drain, partly because I couldn't see it (really just because I forgot and not seeing the bottom didn't remind me of it), but after noticing the robot getting stuck in that vicinity I would move it by hand. After the first two sessions, I could almost see the drain and attempted to drop the donut over the drain, and apparently by some stroke of luck I actually succeeded (couldn't actually tell until a few days later when I could actually barely make out the drain/donut, but it wasn't getting stuck so I figured I was close enough).

    So two days ago I re-read about SLAM, took my pool readings (FC - 0, CYA - 0, ph - 8.0 - didn't check the others). So, after checking the Pool Calculator, I then added about 4 more gallons of "chlorine", about a quart of Muriatic Acid, and about 2 pounds of CYA. FC/TC quickly went up to 10+. In the meantime I have been running the robot for 2 hour sessions 2-3 times daily. Also, the pump is on 24/7. The chlorine pump is not adding any "chlorine" automatically, only what I add manually.

    The current pool temperature is about 66-68 degrees F.

    I checked the FC/TC yesterday morning and it was still about 10 - I didn't check anything else.

    This afternoon I checked and the FC was 3.0, TC was 3.5, TA was about 40, CYA was still about 0, and pH was down to a nice 7.2. Still vacuuming. The water is just slightly clearer (I can make out the donut over the drain and follow the robot in the deep end), but this seems to be taking too long.

    The robot filters seem to be very full of a light gray fine material, and have been extremely full (about 1.5 pounds of the stuff each session - maybe 8-10 sessions) except for the very last one I pulled out at dinner time, which was finally only about half full.

    There still seems to be a little of the stuff near the seams of the liner - but it looks a little better each time. But the water is still very cloudy.

    So - two questions. I have never opened the filter (Pentair FNSP 36 DE filter) in the 12 years I have owned the pool (some say open and check it each year, others say if it ain't broke don't fix it), and I haven't had any problems so far. Could DE be leaching into the pool? I haven't put in as much DE (about 6 pounds so far) as I have removed in gray material, but the stuff feels/looks like DE. Is there any way to check this without opening and inspecting the filter? What are the downsides to opening up the filter?

    What should I do next?

    I am posting a couple pictures (the deep end, where you can barely see the donut, and the vacuum filters - one clean, one dirty).

    IMG_0737 for upload.jpgIMG_0740 for upload.jpg


    22,468 gallons, IG, 18'x36' vinyl, Pentair FNSP 36 DE filter, Stenner 45MHP10 pump with 15 gallon chlorine tank, TF-100 Test Kit

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    Richard320's Avatar
    Join Date
    Jan 2010
    San Dimas, CA (LA County)

    Re: Pool still very cloudy


    That very well could be DE blowing through a ripped filter screen. Any chance you had any freezing water inside the filter? That could have cracked something. Even a small gap can flow a lot of DE.

    I'd suggest opening the thing up. Its really not that hard. There's a nice tutorial and if you look on youtube, lots of videos showing how to do it. And ifg the insides look anything like this picture, take a picture and post it here!
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

  3. Back To Top    #3
    Mod Squad
    Join Date
    Aug 2012
    DFW, TX

    Re: Pool still very cloudy

    Yeah, I'd say it might be time for a little filter maintenance. Looks like you are averaging about one post per year!

    The cloudiness is an early algae outbreak. The light gray stuff is probably dead algae. Need to add about 30ppm of CYA/stabilizer and need to keep the chlorine level above the minimum level for your CYA at all times or algae will grow. Chlorine CYA Chart

    For now, to get rid of the algae you will need to SLAM Your Pool

    Here are some of my fave Pool School articles about how to maintain your pool water after the SLAM.
    TFPC for Beginners
    ABC's of Pool Water Chemistry

    Here are the Recommended Levels for your pool.
    Here are the Recommended Pool Chemicals and how to add it.
    Use PoolMath to figure out how much to add.
    TFP Moderator
    If TFP helped you or saved you money - Become a TFP Supporter! <--Click here
    2012 build and pics, 20k gal gunite, black onyx pebblesheen, OK flagstone, IntellifoVS, cart filter w/Pleatco, IC40 SWG, Solartouch, 5 12'x4' solar panels, HP50HA heat pump, 8mil solar cover, borates, TF-100 test kit, SONOS, Doheny's Discovery Robot, hot tub on bleach

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    Re: Pool still very cloudy

    OK - opened the filter and there it was - a big crack in the top manifold. Since the filter is now 12 years old I decided to go ahead and replace the whole assembly, just in case any of the filter grids were torn. I will take the old unit apart later and salvage anything still usefull. Since I am in a hurry to get going I overpaid the local pool place as they had the whole unit in stock.

    I will post the picture of the crack tomorrow, but the unit in general didn't look too bad. Installation wasn't very difficult either. I also replaced both O rings.

    Thanks for the advice.

    22,468 gallons, IG, 18'x36' vinyl, Pentair FNSP 36 DE filter, Stenner 45MHP10 pump with 15 gallon chlorine tank, TF-100 Test Kit

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    In the Industry
    duraleigh's Avatar
    Join Date
    Apr 2007
    Sebring, Florida

    Re: Pool still very cloudy

    I'm happy things are working for you but you are overdosing the chlorine massively......and I mean massively.

    Your 4 gallons of chlorine that you put in your pool raised your FC to 23 ppm. That FC in a pool with no CYA is actually VERY capable of bleaching your liner.

    I am not trying to change you from what you are doing but I caution all TFP's to measure carefully and consider your dosages before you put them in.
    I have never opened the filter (Pentair FNSP 36 DE filter) in the 12 years I have owned the pool (some say open and check it each year, others say if it ain't broke don't fix it), and I haven't had any problems so far.
    Really? Does the vacuum cleaner in your house ever get emptied and cleaned? It is the same principle. Who says "if it aint broke....."? That just doesn't make sense.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  6. Back To Top    #6

    Re: Pool still very cloudy

    First, the filter assembly, and a closeup of the broken manifold.

    IMG_0742 for upload.jpgIMG_0743 for upload.jpg

    And 16 hours after replacing the filter assembly - sparkling clear.

    IMG_0745 for upload.jpg

    22,468 gallons, IG, 18'x36' vinyl, Pentair FNSP 36 DE filter, Stenner 45MHP10 pump with 15 gallon chlorine tank, TF-100 Test Kit

  7. Back To Top    #7

    Re: Pool still very cloudy

    Dave S., thanks for the tip about my chlorine levels when opening my pool. I went back to the pool calculator and noticed some items near the bottom I hadn't seen or understood before, and noticed I can use those to calculate how much chlorine I need to SLAM my pool on opening the pool - 2 gallons should be sufficient from now on to get my chlorine level to 10 ppm. We have a light blue liner and luckily I have "only" been doubling what I need and so far haven't noticed any discoloration. But I guess I wasn't creative enough in my thinking to figure out how to use the pool calculator to help me with that.

    But this is one of the things this forum has helped me do very well - reduce all chemical usage (and costs). We have the pool covered with a solar blanket probably 90% of the time, and no matter how hard I try I can get all of the other measurements pretty well balanced except CYA - mine is almost always 0. But I will do dome more reading and see if I can figure that out. However, my chlorine usage is relatively low (I think), considering no CYA. I put in via the pump about 1 quart of 12.5% Sodium Hypo per day to keep my FC between 1.5-2.5, and that seems to keep the pool algae free.

    Now, as for opening up the filter regularly, let me say that when the pool was installed I got two different opinions from the installers on how to deal with it - one said to open it up yearly, and one said not to open it up unless there were obvious signs of failure. And even after opening it up this year, which was not nearly as bad as I had imagined, I am still not sure I will do it yearly. You asked if I check the vacuum cleaner (rhetorically, I guess), and the answer is yes. But do you open your catalytic converter regularly to check on that? Your fuel injectors? Your pump motor to check for worn bushings or motor windings? Probably not, even though those are also the same principal. If you are familiar and comfortable with pool filter repair then it makes sense to do that, but I bet most folks don't inspect their filters regularly, and that's probably a good thing. I am not really all that bothered with having spent about $400 for everything (purchased locally - I know it would have been about half that amount if I wanted to wait a week), since that comes out to only a little over $30/year for the 12 years I have owned the pool. And in retrospect, it is now obvious what happened.

    But I will probably open it up every 2-3 years to clean off the grids, and if the pool isn't clean in just a day or 2 I will check the manifold.

    Thanks for the information.

    22,468 gallons, IG, 18'x36' vinyl, Pentair FNSP 36 DE filter, Stenner 45MHP10 pump with 15 gallon chlorine tank, TF-100 Test Kit

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