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Thread: Thick black grease at water line -- and algae in one spot on bottom of cover

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    Eva's Avatar
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    Thick black grease at water line -- and algae in one spot on bottom of cover

    There's a problem in my new-ish pool. Hasn't been a year yet, and I've been having great luck with the TFP method. And my chemistry is just right. This morning FC 4.0, CC 0.5, pH 7.5.

    So, there's this thick black grease on the tile all along the waterline, like a dirty bathtub ring. I can scrub it off with a scouring pad but it just re-deposits, and it doesn't wash off the scouring pad in the washing machine, either. I suspected the motor for the pool cover, but I called the company for service and they took a look and it wasn't throwing out any grease (and was greased with clean white lithium grease). Then I tried to convince myself that it wasn't actually grease, but algae -- it isn't. It is dirty thick grease. Not sunscreen or hair conditioner, but some kind of petroleum. So where could this be coming from, and why? The pool doesn't get heavy use, just me swimming every day and a few friends on the weekends. The pool cover guys tried to tell me to get some "oil be gone" product at the LPS but of course I'm not going for that, as I want to figure it out.

    Another issue, the very expensive pool cover has a single line of algae on the bottom, in a fold (about 1 inch by 4 feet) that has never relaxed. The pool cover guys say they've never seen anything like it, but of course in the inside of the fold does not touch the water to kill the algae, and the cover is a bit translucent, as you can see the pool light through it if you forget to turn it off at night. I've tried weighting the crease down with wet rugs, and walking on it, but it has never relaxes for good. Pushing it down does get the algae wet and kills it and causes pieces of it to fall into the water, but I need to convince the cover guys to get the crease out of there for good. Anyone had a similar problem?

    Many thanks for all your help.
    Eva in Tucson, 9800 gallons IG, under full roof, also with vinyl cover, pebblefina, Pentair 1 HP pump, Pentair 320 sq ft cartridge, Aquacomfort 1150 heat pump, ozonator, Maytronics Dolphin Triton robot. Brand New June 22, 2015!

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    Texas Splash's Avatar
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    Re: Thick black grease at water line -- and algae in one spot on bottom of cover

    Sounds like you are referring to a scum line. Essentially it's a think black line that can start to build-up along the waterline and in the skimmer. It typically comes from oils that have accumulated in/on the water. Why now you ask with little to no swimming? Hard to say. If it's any consolation, I just had a ring develop in my pool over the past couple weeks, and I haven't been in it at all. But even though we're not swimming yet, I suppose the environment and air carry products seasonally that can contribute. Simply scrub it off and you should be fine. Folks use a variety of things like Magic Eraser, or a paste of baking soda on a green kitchen sponge. If it gets really bad over the season, you can purchase something like like a "Scum Ball" that you toss on the water, and eventually sits in the skimmer, that will help to absorb those oils.

    As for the crease in the cover .... hum .... would a quick ironing help maybe?
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
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    Mod Squad kimkats's Avatar
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    Re: Thick black grease at water line -- and algae in one spot on bottom of cover

    LOL "Honey why is the ironing board by the pool?" BUT I wonder if it would work??? Or maybe a blow dryer to warm it up then pull it out and hold the "pull" until it cools off?

    The scum line----have you used ANY algaeicde? Some people have reported a "gummy", dark film on the waterline from some of them.

    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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    Eva's Avatar
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    Re: Thick black grease at water line -- and algae in one spot on bottom of cover

    I am pretty sure, even as a pool newbie, that ironing a motor-driven cover on a track is not the way to go!

    Of course I am swimming now - have the pool heat cranked up and it's lovely. So great.

    It just seems like too heavy a grease for just body oils and lotions and potions. If you rub it with a finger you just move it around -- you can take it off with a scouring pad but it really requires probably simple green. I'm just afraid that some piece of equipment is throwing out grease. Is the stuff you are talking about thick like bearing grease (or petroleum jelly)?

    Many thanks!

    - - - Updated - - -

    No, haven't used any algaecide, or anything else other than acid and chlorine. It's really thick like the kind of grease you'd use to pack bearings. Seems so odd.

    Just don't want it to be some piece of pool equipment throwing out grease as it self-destructs.
    Eva in Tucson, 9800 gallons IG, under full roof, also with vinyl cover, pebblefina, Pentair 1 HP pump, Pentair 320 sq ft cartridge, Aquacomfort 1150 heat pump, ozonator, Maytronics Dolphin Triton robot. Brand New June 22, 2015!

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    Mod Squad kimkats's Avatar
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    Re: Thick black grease at water line -- and algae in one spot on bottom of cover

    I would think about having the PB or cover people out to take the cover apart as much as possible to check the motor and stuff for the cover to make sure there is NO grease that can come out. It almost has to be the cover motor but........best to check like you are thinking.......do NOT want something to seize up!

    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: Thick black grease at water line -- and algae in one spot on bottom of cover

    The scum line that develops around our pool from time to time, even in one corner right now, is like tar. It doesn't come off unless you use a Magic Eraser, baking soda paste, or some other product. I also get it inside the skimmer from time to time. That's with zero swimming so far this year. It just happens. The water is picking-up debris and other particulates all the time, so we have to adjust depending upon swimmers load and weather. Now if your pool is covered most of the time, I know it will cut-back on FC usage, but I'm not sure what effect it has on other environmental conditions. But what you are describing sounds just like our typical pool scum line. If you find there is a mechanical issue that is failing and confirmed as responsible, please let us know the details. Others might benefit from that issue. Have a nice day.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
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    Mod Squad kimkats's Avatar
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    Re: Thick black grease at water line -- and algae in one spot on bottom of cover

    Pat that is very interesting! Thanks for sharing..........I wonder if the kinds or trees around the area has anything to do with it?

    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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    Texas Splash's Avatar
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    Re: Thick black grease at water line -- and algae in one spot on bottom of cover

    I live out in the country with no trees on my property, although there certainly are plenty in the local area. Not sure if it's a factor, but we're currently experiencing a high oak allergy/pollen period right now. But every year I can expect to see a scum line accumulation at some part of the waterline. Usually it seems to show-up in the same corner of our pool where the prevailing winds push the water towards that corner - and I'm assuming also push surface debris and/or particulates. It has popped-up at various times of the year, with no changes to my chemical treatment or readings, just kind of "shows-up". We clean it, and it may not return for the rest of the season, or it may come-back 2-3 times. I haven't cracked that code yet, and am not sure I will. While there is no doubt swimmer's load is a factor in a pool's scum line, I think our local weather and stuff in the air (eventually settling on the water) is also a player in that issue. That's getting more into the "deep" stuff though, that's better suited for JoyfulNoise or Chem Geek.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

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    Re: Thick black grease at water line -- and algae in one spot on bottom of cover

    ]I've had a blackish oily substance on the top rail of our pool before. I thought maybe it was because we live near a highway. ?? It wasn't thick or solid, just a little bit, but noticeable.
    26' X 52" Intex Ultra Frame. Intex Sand Filter
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    Eva's Avatar
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    Re: Thick black grease at water line -- and algae in one spot on bottom of cover

    Hi Kim,

    First thing I thought of too. Cover folks came out and their motor is squeaky clean.

    - - - Updated - - -

    Thanks all. I'm going to scrub it off completely (probably using simple green to actually break it up), note the date in my logbook, and see what happens next. Many thanks.
    Eva in Tucson, 9800 gallons IG, under full roof, also with vinyl cover, pebblefina, Pentair 1 HP pump, Pentair 320 sq ft cartridge, Aquacomfort 1150 heat pump, ozonator, Maytronics Dolphin Triton robot. Brand New June 22, 2015!

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    Re: Thick black grease at water line -- and algae in one spot on bottom of cover

    Well Eva, we have been having the same problem with our pool since inception in 2001. Every few days, the black line appears on the side of the pool opposite of prevailing winds and needs to be scrubbed away, and we have found that Magic Eraser works best. But last August, we decided to document everything that could possibly be CAUSING it -- nothing is ruled out until it is tested. We have documented the wind speed and direction, rain/inclement weather, and although at first there seemed to be some kind of correlation, it wasn't consistent, so we had to rule those out. Lots of experiments were conducted regarding vegetation, but we could not get the black line to stop appearing. We recently capped the overflow drain to the Intracoastal, and bought another filter to switch out each time the pool is cleaned. Again, it seemed promising at first, and we actually had 5 days without a black line appearing, only to find it back again. We cut the autofill to see if perhaps a leak was present that would allow any substance to come into the pool. Nothing. With the autofill off, outflow line capped, we started to check the filter each day, and found that black substance in the filter after only one day. After two days it was worse -- not disgusting or anything like that, but it was definitely there and the filter should not be that dirty after only a day or two. So this past week, we shut off the filter altogether and surprise, surprise -- no line whatsoever for this past week. So we're thinking it has something to do with the pipes in the filtration system, or some kind of leak in the equipment perhaps. I just read yesterday in a thread in another forum called Poolhelpforum.com, where someone had copper pipes replaced with PVC pipes and started to have this exact same problem. I've been researching the internet for some answers, but to no avail, and came across your problem. Perhaps we can further brainstorm, or if you would like to call me directly, please feel free to do so at 772-532-4468. I'm in eastern standard time.

    By the way, over the years, we have had every kind of expert look at this pool (engineers, landscapers, water-testing companies, pool repair companies) and have had several pool cleaning companies service and counsel us about this problem. One of the main things they would come up with is, it is coming from the environment (planes, pollution from boaters, etc.) Well, we're pretty far from the airport, and there aren't a lot of boaters that come by, and the black line appears when no boating has occurred. In addition, we created the same vegetative environment around another pool we have that is close to the ocean, and nothing happened -- and that pool is very close the airport. Plus no other pool in our area has this problem.
    Gail R. Tequesta, FL. 2001 Outdoor, inground marcite concrete pool with tile on concrete through the pool. No enclosure, next to Intracoastal, Hayward Filter w/Pleatco Advanced Filters, FloPro pump, 2.00 HP, spa with Jandy system. 2 skimmers, 1 bottom drains, 1 cleaner, autofill, overflows to Intracoastal. Cleaned twice per week with system vac, but have also cleaned once per week with Hammerhead.

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