Stains or something more sinister?

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H

HeritageCove

0
Aug 17, 2010
41
Orlando, Florida
I have dark areas all over the pool (the majority of the pool, ranging from greenish brown to black)--they start about a foot down from the top edge in the shallow end, a couple of feet down from the top in the deep end, and then randomly on the floor, stairs, and steps in the deep end. It doesn't go away with brushing (I have a wall whale, so I'm getting lots of pressure).  It doesn't feel like anything (ie, it doesn't feel slimy).  Is it safe to assume that it's staining from metal-based products in the past or some sort of treatment that was applied to the Pebble Tec?  How can I be sure?  Is there anything else it could be?  Do I need to get a professional to come out and look at it?  I just want to be sure that it's safe to go in there once the test results are in range.
 
Here's the history in brief:  I have been fighting algae since I bought the house in December (never been swimming in it :( ).  Gave up for awhile and let the frogs live in my backyard swamp.  Finally found this site and am getting it cleared.  Currently, it looks pretty clear until I brush (which I am doing 1-2x per day).  I am maintaining at shock level (consistently since I got my test kit on Monday) because I am assuming that the cloudy stuff I am brushing is dead algae.  The pump has been running 24/7 for about 2 weeks.  The pressure is only about 2 over starting pressure.  I drained a couple of feet this weekend because the last pool store test results showed I had a CYA of 100-141.  I switched from pucks and cal-hypo about 1 1/2 weeks ago and now am only using 6% bleach.
 
With my Taylor k-2006,
FC: 13.5 last night, added 50 oz 6% bleach to bring up to 15*. Did NOT test 30 min after adding chemicals.  This morning before the sun hit it, FC was 15.  I added 142 oz of bleach to make sure that it stayed at shock level throughout the day, but still below "high shock" of 24.  I will perform the overnight FC loss test tonight/tomorrow if possible (actually, is there any point in doing that if I'm still getting cloudy stuff off the bottom and sides when I brush?).
CC: < or = .5 this morning
TA: 110
CH: 330/340
CYA: 40
pH: 7.5/7.6
 
*Note: I am having some issues estimating the volume of my pool--I had been assuming it was 17,000, now I am assuming it is 16,000.  It's an irregular shape, so I took several measurements and used the TFP's Pool Calculator to get the 17k, but the first couple of times I used the test kit, I was getting higher FC numbers than expected (specifically, the FC was at 10, I added 192oz, which should have brought it up to 15.5, but it was at least 17 when I tested an hour later).  I'm still a newb with my test kit, which arrived on Monday, so the discrepancy may be due to my inexperience and not incorrect assumptions about the pool size.
 
I would try not to stress about it until the pool is clear. There are many things it could be, but given that it's been a swamp for some time, the most likely explanation is organic stains, which chlorine will remove (though it may take a little while even after the pool is clear of all algae). If they remain after the pool is clear, then you can do some further tests to move forward.

Next time the chlorine is below 10, take a pH reading just to be sure of it. FC above 10 messes up the pH and causes it to read higher than it actually is. I think you're OK, but it's always better to be certain.

Sounds like you're on the right track!
 
If it's algae and not some other type of stain, you may not be shocking high enough. If you put your results in the pool calculator assuming a CYA of 40, then shock level is 15, but to clear mustard algae it's 24. The numbers are even higher if you use your original CYA numbrs of 100 - 140. I would try shocking at a higher level to see what happens or post picks of your stains so others can weigh in if they had something similar.

Good luck
 
I hate to say it, but it sounds like black algae to me. Can you post up a pic?

If you let your pH get out of whack pretty good for a while, there is a good chance that allowed it to take hold. Pebble pools trend high on pH, and they will grow black algae pretty easily if you don't keep them in check. You can beat it, which is a good thing.

I'll attach a pic of a pool I built down in Cabo a couple years back. Somebody sold them on a copper based system, which obviously didn't work! I went down and stayed onsite and walked out to see the pool the first night. Black algae everywhere, and pH off the scale! No acid was being added whatsoever. We've since brought it back (although they are still using the copper, last I heard :evil: ), so I know it is possible! It will take proper water balancing and lots of brushing (get a stainless brush) though!
 

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I think you're getting ahead of yourself. Once you're sure that you're finished shocking (overnight FC loss <1, CC<0.5), then I would start thinking about other things.

Organic staining will fade when a chlorine tablet is rubbed on it. Iron stains will fade when a vitamin C tablet is rubbed/left to sit on it. Black algae will be killed by chlorine; brushing with an SS brush helps. Copper stains will not typically respond to any of the above, and they tend to be bluish/grayish in color. As you mentioned, some pictures will help.
 
Ok, here's a pic near the top edge. [attachment=0:1l73gw9j]Contrast_top edge_082510.JPG[/attachment:1l73gw9j]

Upon closer inspection, I'm thinking it's probably just the way the pool is colored. Maybe parts of it got bleached out, somehow?? There's a very sharp contrast near the top and then it's more random throughout the bottom of the pool. Previously, I thought some of it was black, but now I'm not so sure. It will probably be the weekend before I can see the pool in really good light.
 

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Most of it looks like these:

This the first step...
[attachment=2:w9cd20xn]First step_082510.JPG[/attachment:w9cd20xn]

This one's blurry, but you can see the contrast that is dark at the top edge and gets white. You can't see it, but it gets dark again a little lower. (This is under water so the very top edge is a reflection.)
[attachment=1:w9cd20xn]Blurry contrast_top edge_082510.JPG[/attachment:w9cd20xn]

Here's more...
[attachment=0:w9cd20xn]More contrast_082510.JPG[/attachment:w9cd20xn]
 

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And then there are a few random spots, but they are not the norm...

[attachment=1:1ske6mvs]One small spot_082510.JPG[/attachment:1ske6mvs]

And another:
[attachment=0:1ske6mvs]Another small spot_082510.JPG[/attachment:1ske6mvs]
 

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Since you haven't had the pool for very long, it is hard to know how it was or was not maintained prior to you getting it. Since your CH levels are heading towards the high side of "acceptable", and you have drained some recently, I wonder what your fill water levels are, and how long the water was in the pool before changes.

The good news is that it is not black algae, nor does it appear to be algae at all. That means you are doing a great job of cleaning it up :goodjob: That being said, I would have to agree with crewchief47 and say that you either have a hard water build up or scaling from high pH possibly.

While I try and never suggest draining a pool, you need to do just that and acid wash your pool. Because you have "Pebble", it will handle an acid wash, if properly done. That should clean you right back up and give you a beautiful surface in which to apply your BBB skills to and have a pool that you are proud of.

Try and lower the water level a little bit (or dump the spa (if you have one) water in to the pool and try to acid wash the spa. Be careful and try not to breath to much of the fumes, and rinse and vacuum the acid/water with a shop vac. If that works in the spa (and I suspect it will) you have your answer!

Keep us posted!
 
There's so much to learn!!!
 
A few more follow-up questions:
 
1.  If it's calcium scale, is it safe to swim in?  (as I have not yet gone swimming in this pool, this is my primary concern)
2.  Is calcium scaling more of an aesthetics thing vs a danger thing?  In other words, can I enjoy the rest of the season and deal with this next year?  What's the worst case scenario if I do that (dangers to swimmers, pool surface, or moving parts)?
3.  Based on my reading, it seems possible that the cloudy stuff I'm pulling up with every brush stroke is calcium and not algae?  How do I know the difference for sure?
3.a. If the cloudy stuff is calcium and not algae, is that something I will have to deal with until I drain/acid wash the pool or can I do enough brushing or vacuuming to make a difference (any specific advice on this would be greatly appreciated)?
4.  Can I test that it's calcium with a pumice stone in a small spot or a weak mixture of MA?
 
Just as an FYI on the process, I "high" shocked my pool last night (raised FC to 24), lost 4ppm this morning before the sun hit it, so I "high" shocked again.  I didn't have time to measure, so I added the full 182oz to shock to 25.2.  Unless anyone thinks otherwise, I will start letting the level drop to normal shock (FC 15).  I'm still shocking because I found a nugget of green algae under the last rung of the ladder and the ALL ALONG the rim of the pool, under the edge.  I scrubbed the rim Cinderella-style for about an hour last night.
 
Thanks everyone for the input!  I feel like I am slowly getting a grip on this pool thanks to everyone's help (and, of course Pool School).  
 
Calcium scaling will not cause any problems to you, so it is safe to swim. It will, however, cause damage to your pump shaft, heat exchanger, etc. if it is allowed to build too much. You are under the recommended level (400 ppm) on the high side of CH now, so not an immediate worry. What was done prior to getting this is done.

Calcium scaling is not attractive, so at this point it is aesthetic. See above answer for the other answers!

Algae is usually not white, and most of it comes off pretty easily. By your description, this is not algae (although you do have some/something if you are losing FC overnight still).

Lowering the pH will "loosen" the build up a bit, but not much. The best case scenario is that it will put whatever you do loosen back into suspension, so it is really still in there. The fix is to get the hard water and hard water build up out, and you can either do a drain and acid wash, or an "in pool acid wash", but that will then require an R/O treatment (not available in all areas) to remove the calcium that is now in suspension.

Yup. The stones are durable. Be careful with the plaster matrix that is holding the stones in (the pumice stone won't hit it but to long of exposure/too high acid concentration can). Start with maybe 10% acid to water (always add acid to water!) and see how that works. You can increase strength slowly if you need to, but I would work with as low of concentration as possible to minimize problems.

Get your chemistry finished and keep going until you don't have the overnight loss anymore. Enjoy that pool for what's left of the season, and keep it up over the off season so that you don't have to go through this part again! Then do the drain and acid wash next spring and follow BBB for a great summer :goodjob:
 
Wow! That is some macho scaling...sorry to see that :( Such are the joys of taking over a previously mismanaged pool....

Bruce is most certainly right; an acid wash is required to restore it to its rightful beauty. It'll feel much smoother to boot!
 
Well, I only lost 2ppm in my overnight FC test, so I'm really close. I can live with an unattractive pool for a little longer. A friend of a friend does acid washing professionally, so I will have her take a look at it and then make those arrangements for next spring. Thanks again! I was lost without this forum!
 
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