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Thread: Green stain on pool

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    Green stain on pool

    Hi and thanks for all the info on this forum, I've found it so useful.

    I bought a place with a pool last year. The house kind of came with a pool guy so I kept him going but a couple of months ago he just stopped coming, didn't tell me, and as it was raining and the cover was on I didn't notice that my pool became an algae swamp. A friend of a friend who is a pool guy helped me get rid of the algae, clean my DE filter, replace the grids.

    The pool is now clear but green. The guy helping is now away but he thinks it is still algae and suggested Yellow Out and shock. I did that with 3 1/2 gal of 10% chlorine and brushed the pool walls to no effect. I currently have no chlorine according to my K-2006, I assume b/c it was used by the Yellow Out. I'm about to get more. My chlorine was 8ppm before the shock b/c my CYA is high (Using 3:1 dilution is looks like the CYA is 140). Both pool guys said not to bother draining the pool just use more chlorine. Having read this forum I'm not sure that's a great way to keep going.

    I'll try to attach a photo of the staining, you can see it on the grout. I don't know if it is algae or metals but it doesn't scrub off easy (or at all with a regular pool brush). I haven't used a wire brush yet as I am concerned about damaging the concrete.

    Any thoughts on if this is algae and how to resolve?

    Thanks.

    IMG_4802.jpg

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    Mod Squad kimkats's Avatar
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    Re: Green stain on pool

    Any water restrictions in your area now? If not please use Pool Math as seen in the blue oval at the top of the page to see how much water you need to drain and refill to get your CYA down to 30. THEN we will work on the stain.

    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: Green stain on pool

    Before I found this website the jewelry store, I mean pool store would always tell not to worry about CYA numbers. Why, because they want to sell you pucks at $130 a tub.

    If you can, maintain this pool yourself, much cheaper in the long run.
    15,000 gal In-Ground Vinyl, Jacuzzi Laser Sand Filter w/ 1.5hp Pump , Polaris Cleaner w/ 1hp Pump, Taylor K-2006-C Test Kit

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    Re: Green stain on pool

    In a small plastic measuring cup use a small amount of muriatic acid and pour on tile grout above waterline. Let set for 20 to 30 seconds and see what happens. Those stains definitely look like copper

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    Re: Green stain on pool

    Quote Originally Posted by kadavis View Post
    In a small plastic measuring cup use a small amount of muriatic acid and pour on tile grout above waterline. Let set for 20 to 30 seconds and see what happens. Those stains definitely look like copper
    I poured a little muriatic acid on the grout and the green dissolved. Does that mean it's copper? Is there a way to treat that with water in the pool or would it require an acid wash? I'm looking for a short term fix if I can get one because I am renovating the back of my house in the fall and the pool will probably get messed up from the debris so I'd like to do a proper fix (drain, maybe replaster) after that work is done.

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    Re: Green stain on pool

    Yes those are copper stains and if the pool is really old it might have been plumbed with copper pipe.Need to see more of the plaster, from what I can see it looks pitted also. A acid wash will only do so much and if you have to burn out the stains you definitely will be replastering. Can't really say if a no-drain acid wash would work, you might have to contact someone like Jack's magic and do a topical test on the surface.

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    Re: Green stain on pool

    Quote Originally Posted by kadavis View Post
    Yes those are copper stains and if the pool is really old it might have been plumbed with copper pipe.Need to see more of the plaster, from what I can see it looks pitted also. A acid wash will only do so much and if you have to burn out the stains you definitely will be replastering. Can't really say if a no-drain acid wash would work, you might have to contact someone like Jack's magic and do a topical test on the surface.
    Thanks. Yes the pool is pretty old and the plaster is peeling off the steps and bubbling in a few places, so I don't think an acid wash will do anything but destroy it, so a replaster is probably my only recourse, which I plan to do late this year. For summer I'll try draining some water out and see if I can get my CYA manageable, so at least if I try something like Jack's Magic is will have a better chance of doing something in the short term.
    12,000 gal plaster IG, DE filter, Taylor k-2006 test kit

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    Re: Green stain on pool

    Quote Originally Posted by stewartt View Post
    Thanks. Yes the pool is pretty old and the plaster is peeling off the steps and bubbling in a few places, so I don't think an acid wash will do anything but destroy it, so a replaster is probably my only recourse, which I plan to do late this year. For summer I'll try draining some water out and see if I can get my CYA manageable, so at least if I try something like Jack's Magic is will have a better chance of doing something in the short term.
    Look into AquaBright for your renovation. Seams to work better in old pools and make them last longer. Your chemistry would be like a vinyl pool. Much easier.

    Felipe
    7,500 gal Rectangular, Easytouch 8, Air+water temp sensors, Screenlogic2, IC40, intellibright5g color12v, Intelli pH, SD 70 filter w/Zeolit, Magicstream Laminars, waterfall. Raised Monolithic concrete lined with glass beads.

    In Sunny Monterrey,Mx!

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    Re: Green stain on pool

    Just wanted to say thanks for the advice. I ended up draining my pool about 2/3 to get the CYA down. It is now at 60 so it's still at the high end, but I was able to measure to SLAM effectively. In doing so, most of the green color disappeared and my pool is now about the same blue-ish color it was before the algae. This will see me through the summer so I can drain fully and replaster in the winter. Not going back to a pool service.
    12,000 gal plaster IG, DE filter, Taylor k-2006 test kit

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