Pool Stain Help Requested

[glesniak]

I have an odd stain problem I have been unable to rectify. I'm not even sure if "stain" in the correct terminology as this seems to be more of a deposit. I have small, the size of a head of a pin, reddish-brown spots on the vinyl liner and fiberglass stairs of my pool. In many cases I can pick them off with my thumb nail but not always. I have tried Jack's Magic Stain ID kit with no substantial positive results. I have tried citric acid in a sock as well as vitamin C tabs with some, very minor improvement. A chlorine puck does nothing. PH Down (dry acid) does seem to help, especially on the fiberglass stairs.

Here are my numbers from last season
PH 7.5
Alkalinity 90
Chlorine 4.0
CYA 55

Any ideas?

George

 

[jblizzle]

Usually calcium scale is what adds a texture ... metal / organic staining I think is pretty smooth. Could be a combination of calcium scale with a metal stain on it?

Can you add some pictures that may trigger someone's ideas?

 

[glesniak]

I was wondering about calcium as a possibility as well, however I am unable to get a stable CH reading with my TF100.

I don't have photos of the deposits but I do have some underwater videos. They are a blurry as the camera didn't want to focus up close, but you will be able to see the pattern of the deposits. The videos are shot from about 6"

This is a shot of the deposits on the stairs
https://www.dropbox.com/s/dr25p5g5exr65uw/100_0021.AVI

And on the liner
https://www.dropbox.com/s/mlkexmvdm8x5vot/100_0022.AVI

The smaller deposits are about the size of the head of a pin. The largest deposits are less than 1/8" diameter.

Thanks for your help, I appreciate your input.

 

[jblizzle]

I can not look at the videos now ...

But, what is going wrong with your CH test? Describe your process, what your are seeing, etc

 

[Richard320]

How long did you leave the puck on? Because those sort of look like black algae, and the FC level you show is a little low for your CYA.

 

[glesniak]

I can not look at the videos now ...

But, what is going wrong with your CH test? Describe your process, what your are seeing, etc

I follow the instructors in the kit, 20 drops of R-0010 and mix, 5 drops of R0011L and mix. The solution is RED. I add R-0012 one drop at a time but I get wildly different results each test. It takes 11 - 30 drops to turn BLUE and sometimes it will not turn BLUE at all, just GREENish. I have tried the copper process with similar results as we did have a Nature2 when the pool was built in 2010 but that has been gone for more than 2 years.

 

[jblizzle]

Hmm. Maybe I do not see that problem because I have a Speedstir so I can just quickly count the drops for the color change and not worry about trying to swirl the vial.

 

[glesniak]

How long did you leave the puck on? Because those sort of look like black algae, and the FC level you show is a little low for your CYA.

I have tried more than once with a puck, 10 - 30 minutes. No appreciable results.

CYA is another test I have trouble getting consistent readings. I have even tried taking multiple water samples to 3 different pool store and even their readings are inconsistent. (which is why I bought the TF100 in the first place )

Silly question; is black algae black? These stains are definitely reddish brown, similar in color to rust.

 

[jblizzle]

If you pick one of them off can you smear it at all on paper? Or is it hard?
Black algae is pretty black I think, but when smeared will look dark green.

 

[glesniak]

Hmm. Maybe I do not see that problem because I have a Speedstir so I can just quickly count the drops for the color change and not worry about trying to swirl the vial.

I wll order a speed-stir when I re-order kit supplies and try again.

 

[glesniak]

If you pick one of them off can you smear it at all on paper? Or is it hard?
Black algae is pretty black I think, but when smeared will look dark green.

No, they do not smear. They are hard and crumble into fine particles.

 

[jblizzle]

I think that makes it sound more like a scaling issue, maybe with some iron staining???

 

[Swampwoman]

Hi George. My pool is still snow-covered at the moment, but your spots look a lot like what I get in the stair area plus what I've assumed to be a few historic rust stains from before we owned the pool.
My suspicion is oxidized iron combined with scale. An Ascorbic Acid treatment did not completely remove them.

I don't know if this is advisable, but I've been thinking once I get the pool open I'd like to try a combo of ph down with ascorbic acid in some kind of "spot delivery system" -- eg a sock with rocks to anchor it and leave it sit for a day. I suspect the scale needs to dissolve before the iron can release.

 

[glesniak]

Here are the test number from this morning. We opened the pool 10 days ago, brought pH to 7.4, TA to 80 and shocked to 15. The CYA and calcium hardness tests were run 3 times each to verify the results. The water is crystal clear with no haze what so ever with the light on at night. The water temp is a bit too low (~50°)to get new pictures of the spots.

FC 7.5
CC 0.5
TC 8.0
pH 7.4
TA 70
CH 200 (180-220)
CYA 70 (65-75) I do not believe CYA is accurate, we were @ 55 last year and replaced ~20% of the old water at start-up this year