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Thread: Continued Sand Filter issues or Hidden Algae Outbreak

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    Continued Sand Filter issues or Hidden Algae Outbreak

    So once again, I struggle with a "clear pool" yet I have a TON of dirt/hidden algae/pollen etc....that keeps it from being crystal clear.

    FC 7.0
    CC 0.0
    CYA 70 (overshot a little but I have automated dosing via a stenner so I am not too worried)
    PH 7.4
    TA 90

    I continually pass the overnight test, last night was 7.5 at 7 pm then at 6:30 AM 7.0

    if CYA was not so high I would slam, but getting to 28 PPM will cost a few more dollars if I am chasing nothing.....

    Dumb question, but is there any other way to know for sure if I need to SLAM or if my continued (perceived) Sand Filter issues prevent me from having crystal clear water.

    I backwash and get no green water...

    I also am not consuming excess FC, just about 2 - 3 ppm daily.
    14,750 GAL IG Fiberglass (16 x 33) NE Ohio || Jandy 1HP 2 speed Pump || Waterco MultiCyclone 16 Centrifugal pre-filter (removed due to not working with sand filter) || 30" 575 Lb. Sand Filter || AquaCal 140K BTU Heat Pump || Solar Cover || Inter-fab Adrenaline Slide || GLI Monsoon Solar Cover Reel || K-2006C Test Kit || BBB with Liquid Chlorine Stenner Injection || Rayner Mighty Mesh Winter Cover

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    Re: Continued Sand Filter issues or Hidden Algae Outbreak



    Thought picture would help....you can see the deep end is NOT SUPER SUPER SUPER Clear, but no green tinge or at least I don't think.

    14,750 GAL IG Fiberglass (16 x 33) NE Ohio || Jandy 1HP 2 speed Pump || Waterco MultiCyclone 16 Centrifugal pre-filter (removed due to not working with sand filter) || 30" 575 Lb. Sand Filter || AquaCal 140K BTU Heat Pump || Solar Cover || Inter-fab Adrenaline Slide || GLI Monsoon Solar Cover Reel || K-2006C Test Kit || BBB with Liquid Chlorine Stenner Injection || Rayner Mighty Mesh Winter Cover

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    Richard320's Avatar
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    Re: Continued Sand Filter issues or Hidden Algae Outbreak

    Two things consume FC: sunlight and organics. You've eliminated sunlight. Assuming you remembered to shut off the stenner during the OCLT, you've also ruled out organics. That leaves filtration issues.

    Have you tried Deep Cleaning a Sand Filter ? Sand can clump and then get broken up into clods when you backwash and they may not settle down right. That leaves wide gaps for the water to sneak through unfiltered. It's called channeling. Give that a go and see how it works for a week.

    If you've already tried that, then try Adding DE to a Sand Filter
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
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    Re: Continued Sand Filter issues or Hidden Algae Outbreak

    Thanks for the follow up...

    I did Deep Clean end of last year, and this year before I started the sand felt and looked fine....I guess I could try again as I did backwash this year a few times.

    I also added some DE, filter pressure increased by 1 PSI with only 1/2 cup, so we will let that run as well.

    I guess a SLAM could not hurt, but I will continue to monitor and report back. Thanks again!
    14,750 GAL IG Fiberglass (16 x 33) NE Ohio || Jandy 1HP 2 speed Pump || Waterco MultiCyclone 16 Centrifugal pre-filter (removed due to not working with sand filter) || 30" 575 Lb. Sand Filter || AquaCal 140K BTU Heat Pump || Solar Cover || Inter-fab Adrenaline Slide || GLI Monsoon Solar Cover Reel || K-2006C Test Kit || BBB with Liquid Chlorine Stenner Injection || Rayner Mighty Mesh Winter Cover

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    frustratedpoolmom's Avatar
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    Re: Continued Sand Filter issues or Hidden Algae Outbreak

    I would repeat the DE in the filter process and repeat it over the course of a few days. Doesn't sound slam worthy to me...
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
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    Re: Continued Sand Filter issues or Hidden Algae Outbreak

    I'm with FPM....I don't think it's SLAM-worthy just yet.
    yet I have a TON of dirt/hidden algae/pollen etc
    So, this is visual evidence? It's not clear to me what you are seeing.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: Continued Sand Filter issues or Hidden Algae Outbreak

    Quote Originally Posted by duraleigh View Post
    I'm with FPM....I don't think it's SLAM-worthy just yet.So, this is visual evidence? It's not clear to me what you are seeing.
    Good question....so last year, after ultimately using slim bags to clear up my pool, I could literally read a quarter taped to the shallow end wall from the deep end (33 feet away)....I did this with an underwater camera that I zoomed.

    This year I hoped normal filtering could get me clear....but it isn't. The water is SUPER CLEAR to the average person, but my TFP eyes said it is not, plus my quarter test fails.

    So I am not sure if my filter is once again not working right (replaced a ton of parts chasing this last year) or I have a minor hidden algae outbreak.

    I did a overnight test last night and I lost 1 PPM of FC, which to me is a bit concerning....yet no trace of Algae or greenness, etc.

    My filter pressure (with a bit of DE) also rose from 15-20 last night, so something is going on. When I backwash NO GREEN, just normal dirt.

    I wonder if a low level SLAM would help, or is that worthless and should I just knock it up to 28 PPM, problem is I am heading out of town, so I won't be able to SLAM till next week....

    Plan is to continue to add DE and FILTER 24 hours to see if this does anything, then when I head out of town set the Stenner to error on the HIGH SIDE of my average lose of 2-3 PPM per day and the when I get back re-evaluate. Does this sound like a solid plan, or any other questions - please ask!
    14,750 GAL IG Fiberglass (16 x 33) NE Ohio || Jandy 1HP 2 speed Pump || Waterco MultiCyclone 16 Centrifugal pre-filter (removed due to not working with sand filter) || 30" 575 Lb. Sand Filter || AquaCal 140K BTU Heat Pump || Solar Cover || Inter-fab Adrenaline Slide || GLI Monsoon Solar Cover Reel || K-2006C Test Kit || BBB with Liquid Chlorine Stenner Injection || Rayner Mighty Mesh Winter Cover

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    Re: Continued Sand Filter issues or Hidden Algae Outbreak

    So I backwashed after running with DE again, and this time I see a slight hint brown/green dirt in the backwash. Algae or not, who knows.

    I would SLAM, but heading out of town....

    Water is beyond clear....numbers all in line.

    Will OCLT again tonight.....
    14,750 GAL IG Fiberglass (16 x 33) NE Ohio || Jandy 1HP 2 speed Pump || Waterco MultiCyclone 16 Centrifugal pre-filter (removed due to not working with sand filter) || 30" 575 Lb. Sand Filter || AquaCal 140K BTU Heat Pump || Solar Cover || Inter-fab Adrenaline Slide || GLI Monsoon Solar Cover Reel || K-2006C Test Kit || BBB with Liquid Chlorine Stenner Injection || Rayner Mighty Mesh Winter Cover

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    Re: Continued Sand Filter issues or Hidden Algae Outbreak

    Hi toofast.....I also live in NE Ohio. Based on your specs and location, I think we share the same pool builder. If I am correct, you have a Thursday pool. Regarding clarity, I struggled with that last year and only fixed it by going all the way to 30 ppm chlorine for about 36 hours. CYA was only 30, so this was an aggressive move, but it worked. I haven't had a problem since. Prior to that I tried adding DE to the filter, cleaning the filter to mend any channeling, testing for phosphates, balancing to CSI of 0, etc. I was extremely frustrated and it was my high school son who convinced me that we had an extremely aggressive form of algae. It didn't cost much to SLAM, as it took 3-4 gal of 12.5% chlorine ($2 per gal on sale at Marc's!).

    Once the algae was gone, it was so clean that I couldn't get the chlorine down in order to swim....had to resort to adding hydrogen peroxide to neutralize it. I was able to see clearly tiny grains of sand sitting on the bottom after I was done.
    16 X 37 Thursday Fiberglass Pool | Jandy 2 speed pump | Sand Filter | Pre filter cyclone | 4 Deck Jets | 2 LED Lights | Mighty Mesh Pool Cover | Salt Water Pool | BBB Method

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    Re: Continued Sand Filter issues or Hidden Algae Outbreak

    Quote Originally Posted by Brutus19 View Post
    Hi toofast.....I also live in NE Ohio. Based on your specs and location, I think we share the same pool builder. If I am correct, you have a Thursday pool. Regarding clarity, I struggled with that last year and only fixed it by going all the way to 30 ppm chlorine for about 36 hours. CYA was only 30, so this was an aggressive move, but it worked. I haven't had a problem since. Prior to that I tried adding DE to the filter, cleaning the filter to mend any channeling, testing for phosphates, balancing to CSI of 0, etc. I was extremely frustrated and it was my high school son who convinced me that we had an extremely aggressive form of algae. It didn't cost much to SLAM, as it took 3-4 gal of 12.5% chlorine ($2 per gal on sale at Marc's!).

    Once the algae was gone, it was so clean that I couldn't get the chlorine down in order to swim....had to resort to adding hydrogen peroxide to neutralize it. I was able to see clearly tiny grains of sand sitting on the bottom after I was done.
    I'm glad you were able to clear your pool, but we would never advocate taking a SLAM to that level with only 30 CYA. Even mustard algae only requires 18 Ppm for 24 hours.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Continued Sand Filter issues or Hidden Algae Outbreak

    When you backwashed you removed all that DE you added, so perhaps that was the brown you saw fly by in the water?
    My Amazon Smile for November12K Fiberglass IG, Infinity 4000 automatic cover, SWCG, Hayward Sand Filter, Hayward 1.5 Pump, Doheny Discovery Robot, Savi Melody LED pool lights, outdoor speakers and other assorted doo-dads. Sundance Altamar Hot Tub.
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    Re: Continued Sand Filter issues or Hidden Algae Outbreak

    Quote Originally Posted by Brutus19 View Post
    Hi toofast.....I also live in NE Ohio. Based on your specs and location, I think we share the same pool builder. If I am correct, you have a Thursday pool. Regarding clarity, I struggled with that last year and only fixed it by going all the way to 30 ppm chlorine for about 36 hours. CYA was only 30, so this was an aggressive move, but it worked. I haven't had a problem since. Prior to that I tried adding DE to the filter, cleaning the filter to mend any channeling, testing for phosphates, balancing to CSI of 0, etc. I was extremely frustrated and it was my high school son who convinced me that we had an extremely aggressive form of algae. It didn't cost much to SLAM, as it took 3-4 gal of 12.5% chlorine ($2 per gal on sale at Marc's!).

    Once the algae was gone, it was so clean that I couldn't get the chlorine down in order to swim....had to resort to adding hydrogen peroxide to neutralize it. I was able to see clearly tiny grains of sand sitting on the bottom after I was done.
    Hey good morning...yes I think we do share the same builder. Where you the customer that came over before you built to check out his work ? Either way, nice to meet you (or meet you again)

    Yeah I think I slipped once early spring....SLAM is starting today. Oh, and thanks' for the Marc's note....I found the same stuff, great deal!

    - - - Updated - - -

    Quote Originally Posted by YippeeSkippy View Post
    When you backwashed you removed all that DE you added, so perhaps that was the brown you saw fly by in the water?
    Yeah, unsure....but I am still getting OCLT of 1 PPM and then after heavy swimming I get a CC of .5, so I will start a SLAM today and then see what happens next.
    14,750 GAL IG Fiberglass (16 x 33) NE Ohio || Jandy 1HP 2 speed Pump || Waterco MultiCyclone 16 Centrifugal pre-filter (removed due to not working with sand filter) || 30" 575 Lb. Sand Filter || AquaCal 140K BTU Heat Pump || Solar Cover || Inter-fab Adrenaline Slide || GLI Monsoon Solar Cover Reel || K-2006C Test Kit || BBB with Liquid Chlorine Stenner Injection || Rayner Mighty Mesh Winter Cover

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    Re: Continued Sand Filter issues or Hidden Algae Outbreak

    After bringing to SLAM levels today, it is 8:30 PM and I consumed nearly 10PPM of FC today....so for sure SOMETHING was going on.

    I was able to swim around 6 PM and the water was already noticeably clearer underwater from end to end. Even though most lay people would not understand!

    My gut says I will pass OCLT tonight, but I might stay at SLAM another day just to make sure.
    14,750 GAL IG Fiberglass (16 x 33) NE Ohio || Jandy 1HP 2 speed Pump || Waterco MultiCyclone 16 Centrifugal pre-filter (removed due to not working with sand filter) || 30" 575 Lb. Sand Filter || AquaCal 140K BTU Heat Pump || Solar Cover || Inter-fab Adrenaline Slide || GLI Monsoon Solar Cover Reel || K-2006C Test Kit || BBB with Liquid Chlorine Stenner Injection || Rayner Mighty Mesh Winter Cover

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    Re: Continued Sand Filter issues or Hidden Algae Outbreak

    Geez...so I lost either 1 PPM or 1.5 PPM last night.

    Looks like another day of SLAMing....but hey that is what this is all about.

    Pool is clearer than ever (will post a few pictures later) but I still must have a bit of the funk going on.
    14,750 GAL IG Fiberglass (16 x 33) NE Ohio || Jandy 1HP 2 speed Pump || Waterco MultiCyclone 16 Centrifugal pre-filter (removed due to not working with sand filter) || 30" 575 Lb. Sand Filter || AquaCal 140K BTU Heat Pump || Solar Cover || Inter-fab Adrenaline Slide || GLI Monsoon Solar Cover Reel || K-2006C Test Kit || BBB with Liquid Chlorine Stenner Injection || Rayner Mighty Mesh Winter Cover

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    Re: Continued Sand Filter issues or Hidden Algae Outbreak

    So to any TPF doubter...even though MOST folks said I was crazy who saw my pool, I knew something was not right.

    After Day 1 of SLAM - still not quite passing the OCLT to my satisfaction.

    14,750 GAL IG Fiberglass (16 x 33) NE Ohio || Jandy 1HP 2 speed Pump || Waterco MultiCyclone 16 Centrifugal pre-filter (removed due to not working with sand filter) || 30" 575 Lb. Sand Filter || AquaCal 140K BTU Heat Pump || Solar Cover || Inter-fab Adrenaline Slide || GLI Monsoon Solar Cover Reel || K-2006C Test Kit || BBB with Liquid Chlorine Stenner Injection || Rayner Mighty Mesh Winter Cover

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    Re: Continued Sand Filter issues or Hidden Algae Outbreak

    Keep it up until you pass the OCLT. We learn our pools and know when something is not right. I has a "senior moment" last year and had my Stenner chlorine pump turned off for 5 days while we were out of town. When I got home I discover the non-existent chlorine and immediately added it. Over the next week the water was still beautiful but I was using more chlorine than usual. An OCLT proved something was growing in the water.

    Trust the testing, even if you have a clear pool. Kill it now and kill it dead.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Continued Sand Filter issues or Hidden Algae Outbreak

    Ok, so now I am p*****d

    I guess first a question, I held FC fairly strong during the day, when I tested 9:45 PM there was a storm about to roll in. All night it rained, and this morning I lost more FC than before, down 2 PPM.

    My pool is clear of course still...

    Could the rain itself cause that, and do I really need to SLAM another day ?
    14,750 GAL IG Fiberglass (16 x 33) NE Ohio || Jandy 1HP 2 speed Pump || Waterco MultiCyclone 16 Centrifugal pre-filter (removed due to not working with sand filter) || 30" 575 Lb. Sand Filter || AquaCal 140K BTU Heat Pump || Solar Cover || Inter-fab Adrenaline Slide || GLI Monsoon Solar Cover Reel || K-2006C Test Kit || BBB with Liquid Chlorine Stenner Injection || Rayner Mighty Mesh Winter Cover

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    Mod Squad tim5055's Avatar
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    Re: Continued Sand Filter issues or Hidden Algae Outbreak

    Quote Originally Posted by toofast View Post
    Ok, so now I am p*****d

    I guess first a question, I held FC fairly strong during the day, when I tested 9:45 PM there was a storm about to roll in. All night it rained, and this morning I lost more FC than before, down 2 PPM.

    My pool is clear of course still...

    Could the rain itself cause that, and do I really need to SLAM another day ?
    I generally look at it that it is better for a SLAM to last a day or two longer and get the problems behind you. It seems that folks who have recurring problems are the ones who are a little too quick to end the SLAM.

    Make sure it's dead and gone.-
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: Continued Sand Filter issues or Hidden Algae Outbreak

    Quote Originally Posted by tim5055 View Post
    I generally look at it that it is better for a SLAM to last a day or two longer and get the problems behind you. It seems that folks who have recurring problems are the ones who are a little too quick to end the SLAM.

    Make sure it's dead and gone.-
    Yep - fair enough....one (hopefully) more day....
    14,750 GAL IG Fiberglass (16 x 33) NE Ohio || Jandy 1HP 2 speed Pump || Waterco MultiCyclone 16 Centrifugal pre-filter (removed due to not working with sand filter) || 30" 575 Lb. Sand Filter || AquaCal 140K BTU Heat Pump || Solar Cover || Inter-fab Adrenaline Slide || GLI Monsoon Solar Cover Reel || K-2006C Test Kit || BBB with Liquid Chlorine Stenner Injection || Rayner Mighty Mesh Winter Cover

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    Re: Continued Sand Filter issues or Hidden Algae Outbreak

    When I had to SLAM back in March due to my own laziness/stupidity, I almost quit too early. It ended up taking 6 days longer than when I was tempted to stop the SLAM. There was something that continued to consume the chlorine overnight - even after what seemed like a good OCLT. My FC levels were into the high 20s and even a small change in sample size can throw off the DPD test when you need to use 50 drops.

    Haven't had a problem since then and I'm glad I heeded the advice here.
    John - 16,000 gallon | in ground | pebble | Triton II sand filter | TF100 | speedstir | Hayward Phoenix 2x

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