Dirt looking stuff on bottom of pool

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silversteed

silversteed

0
Aug 26, 2012
72
Herndon, Va
Pool water looks good, but I have some sort of black stuff on the bottom and it appears to be spreading. I've brushed it several times but it doesn't change/move at all. I've brought the pool up to shock levels, but didn't maintain them there as I didn't have time to do overnight FC loss. The CC's go to 0 though. Should I go back and repeat the shock treatment? Anything else look to be a problem from the pictures?

Thanks for any help,

Jim

FC=3.0
CC=0.5
TC=3.5
CYA=20
CH=230
TA=90
pH=7.5

DSC_1980.JPG

DSC_1972.JPG


Pool water looks clean:

DSC_1974.JPG
 
It wasn't there last year and this is my first year with the pool. Last year starting in August when I took over the pool I didn't have any problems. I do know lots of stuff from the trees was dumped into the pool and it has been a battle just keeping all the leaves and debris out.

Also, I went out and checked the supplies that the previous owner left and I found some polyquat. So there is a possibility that they were having this problem too.
 
Monday I cleaned the filter, vacuumed, and then brushed the pool. Tuesday evening I shocked the pool by putting 242 oz of 8.3% bleach in the pool. After a few hours I measured the FC and it was at 14 (still trying to figure out how many gallons are in the pool, was told 25k/28 but I think it is less). I also hung a sock with stabilizer in it by one of jets using the pool calculator and specifying that the pool was 17k gal so that I knew I wouldn't over do it.

I took a chlorine tablet and rubbed in on some of the spotted areas and it didn't seem to have any effect. I also tried to scrape some up but couldn't get any to come off. It is hard to get to because the pool has a ruff concrete surface. I set a tablet on it for over an hour and there was no difference.

This morning I measured the FC and it was at 11.5. I brushed the pool again and there is no noticeable difference in the black spots (they may be worse). I did notice that there is a spot that looks like it was left behind from a paper clip, I believe there was one in there when I opened the pool this year. Probably dropped by one of the pool guys I had working on it last year.

I believe I should complete the shock process and maybe try some vitamin C on some of the spots. Is this worth doing or am I just being a little impatient?
 
Just looked at the chems that I had the pool store do last year when I bought my house/pool and they showed copper and iron in the pool.

their readings were:
Copper 1.22 ppm
Iron 0.06 ppm

Also, I noticed when I did the CH test that the sample turned purple before it made it to blue, took a couple of more drops to get it to blue.
 
Have you touched the black stuff? Is it greasy? Can it be vacuumed up? If so, I had solar panels on the roof that started "shedding" on the inside and your picture looks like what I had on the bottom.
 
It seems that all the black stuff is in the crevasses in the concrete. I have tried to touch it, scratch it, rub it, scrub it...nothing working. I put vitamin C on it and I have but Chlorine tablets on the and they don't change.

There is a heater hooked to the system that doesn't work...

I got nothing and no idea on what to do
 
Still trying to get something to remove the black spots in my pool. I have kept the CL from 7 - 10 ppm for over a week now after shocking it the previous week. The spots haven't faded at all.

The black spots are contained in the shallower areas of the pool. The only ones that I can see in the deep end are in the swim-out.

Any ideas on what I should try next?
 

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