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Thread: Hard Yellow spots - Algae?

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    Hard Yellow spots - Algae?

    Hi I am a new pool owner, (the pool isn't new, but I'm new too it...) and this is my first post.

    I have some round yellowish spots multiplying in the shallow end of my pool, in an area that gets continual sun during the day, where the vertical pool wall meets the bottom of the pool.
    The pool walls are vinyl, brushing over the stuff with a nylon brush doesn't loosen up the spots or seem to affect them in any way.

    I had my pool water tested by a pool company two days ago. Sorry but I don't have numbers, this is what I can remember, where I don't have the number I give a qualitative response....

    Pool volume 110,000 Litres = 29,000 US Gallons
    PH 8.0 (although my test strips continually tell me 7.4 to 7.6)
    Alkalinity - OK
    Stabilizer - none
    Chlorine - low
    Clarity - clear
    Hardness - not sure

    The pool company recommended a treatment of - liquid chlorine, 2Kg stabilizer, algicide, 50lbs Calcium chloride.
    Since Monday I have

    - put 2Kg of stabilizer in the pool (in a nylon sock, hung off of a ladder)
    - 30L of liquid Chlorine (all on Monday at dusk)
    - 1L Algicide (Monday night as well)
    - 4 treatments of 7lbs of Calcium Chloride, pre-dissolved, spaced by 12 hours each
    - Pool filter had been left on continuously.

    As of Wednesday morning (today) my test strips tell me that Chlorine level is 'High', Alkalinity is good (120ppm), PH is 7.4-7.6

    The water looks really good and I would think everything is great except for these yellowish brown spots that are multiplying. I don't think it is yellow algae because I can't brush the stuff off.
    I will post a picture of the stuff soon, and get another water reading with actual number, but any help would be greatly appreciated!

    Thanks,

    Steve
    ~13000 inground plaster
    150sq Ft Cartridge Filter

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    JasonLion's Avatar
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    Re: Hard Yellow spots - Algae?

    Those sound like iron stains. You can confirm that by holding a vitamin C tablet against a stain for 30 seconds. If it is iron it will either disappear where the vitamin C tablet is or lighten significantly. If it is iron, you will need to use sequestrant and possibly do an ascorbic acid treatment.
    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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    frustratedpoolmom's Avatar
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    Re: Hard Yellow spots - Algae?

    Welcome to the forum. FYI, calcium is not necessary for a vinyl pool. Also algaecide isn't necessary either, we will recommend it certain situations but for the most part chlorine does the job better for less money.

    Let us know what happens with the stains.

    Consider getting the TAylor K-2006 test kit, as strips are notoriously inaccurate.
    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
    http://www.PerfectlyClearPoolService.com

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    Re: Hard Yellow spots - Algae?

    When I got home I realized I didn't have any vitamin C tablets to work with and I neglected to cut open a lime and try it out, but I did take some pictures and jumped in the pool to have a feel around. The spots are not slimey aren't really 'bumpy' either.
    I've attached pictures.
    I went to my local pool supply store today and showed them the pictures. They were quite certain that these are copper stains, and probably a result of putting a product called 'see pool' (they were not sure on the spelling).
    They said I should buy some scale and stain remover product to get rid of the stains.

    Do you agree that these look like copper stains and that scale and stain remover is the best way to get rid of them?

    Also - regarding the vinyl pool and calcium, the pool supply store indicated that to keep warranty on a vinyl lining you are required to keep hardness levels at the correct level (-- whatever.... imo --). They also said harder water will protect plastic pool fittings. I am skeptical, but would tend to go along with this because I am a complete noob.
    Attached Images Attached Images
    ~13000 inground plaster
    150sq Ft Cartridge Filter

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    JasonLion's Avatar
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    Re: Hard Yellow spots - Algae?

    Copper stains do not normally form distinct spots on the wall like that unless several small pieces of copper were held against the wall.

    Try the vitamin C before going to stain remover. Those are small enough spots that you could remove them manually with vitamin C tablets, if that works, for less than the cost of a bottle of stain remover.

    If your warranty requires CH then by all means use CH. CH isn't required with vinyl or plastic pipe, but if they want to see it, keeping your warranty is worth the trouble of adding it.
    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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    Re: Hard Yellow spots - Algae?

    I've tried rubbing a vitamin C tablet on some spots and didn't notice any change in their size or colour.
    I actually have about 100 spots, the picture I've put up is just in one small area.
    I bought some liquid 'stain and scale away'. 2L of it. I dumped 2L of it in one corner of the pool where there were a bunch of spots. I brushed and brushed and brushed but the spots are still there.

    I have some PH reducer, I am thinking about putting some into a sock and letting it sit on top of some spots for a period of time, then seeing if there is a change in the area.
    below is from http://www.askalanaquestion.com/pool_stain_problems.htm

    " When the pool people suggested a "wash", I suspect that they were referring to an acid wash. This type of treatment is periodically done on masonry pools to remove surface deposits and restore the look of the pool finish. It may be possible to remove the stains by chemical treatment. Try this. Put 1/2 pound of pH reducer powder in a white sock, shut off the filter and drop onto a stained area. Check after 15-30 minutes. If improvement is seen, this would be indicative that chemical treatment might work. Chemical treatment will require that you add 2-3 doses of a quality mineral treatment, to help prevent further discoloration. "
    ~13000 inground plaster
    150sq Ft Cartridge Filter

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    JasonLion's Avatar
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    Re: Hard Yellow spots - Algae?

    The third thing to try is a trichlor tablet for about 30 seconds.
    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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