Stains, stains and more stains

[Lankness]

Any help would be greatly appreciated.

Our pool was finished last Memorial Day - gunite pool with arctic white Hydrazzo plaster. Around September of last year we began seeing stains around the main drains. Then they started appearing on the steps. Then they started appearing everywhere. The stains are a grayish to black color and have basically streaked and mottled the entire pool.

Our pH has always been 7.4-7.6. Chlorine has always been between 2 and 3ppm.

I had the water tested at 2 local stores (Leslie's and Warehouse) in efforts to determine what the stains are. Other than phosphates being high, all other metrics were within expected ranges. No metals. I have tried the vitamin C tablet tests, lemons, limes, Jack's stain ID kits, pumice stones - NOTHING does anything to the stains. Our builder couldn't tell us what they are but did determine that direct application of muriatic acid will lighten and eventually remove the stain. The issue is that they come right back within a couple of weeks.

At this point the recommendation was made to drain the pool and have it acid washed. This is hard for us to accept when the pool is <1 year old and has been kept in the 'correct' levels as far as chemistry is concerned. I want to know what the stains are and what is causing them. If acid washing is the solution, that's fine - but I want to know that the stains will not come back.

Again, advice is greatly appreciated. I am hoping someone relates to the pictures and can explain what is going on.

 

[JasonLion]

Welcome to TFP!

Could you post a complete set of water test results?

 

[Lankness]

Two more pictures.

 

[Lankness]

Welcome to TFP!

Could you post a complete set of water test results?

I'll look for them when I get to the house tonight. The tests were done in November and December of last year, hopefully I can find them :|

If not I'll take a sample and get a new work up done at Leslie's.

 

[Lankness]

Shoot - I can't find them...regardless it would probably be best to get some that are more current. Let me see if I can get to Leslie's today.

 

[Richard320]

Looks like scale to me. Check out the pictures in this thread If muriatic acid lifts them, it's almost certain. The fact that the pool is new also means there is likely a lot of CH leeching out of the curing plaster.

Without a full set of accurate test results - and I don't mean from the pool store - it is hard to tell. You may have real high CH, and real high TA, to the point that CSI goes positive despite pH being good. So the calcium starts crystallizing in low-circulation areas.

 

[onBalance]

As a former pool plasterer, the above pool discoloration problem does NOT look like calcium scaling. IF the plaster surface is smooth, that is evident that it is not calcium scaling. Some of the discoloration in the pictures looks like smooth "gray" mottling caused by excess calcium chloride added to the plaster mix, and/or caused by overly late, hard, and dry troweling.

However, some of the dark marks appear to be from something (perhaps) scaping the plaster surface. But I am not sure. It is different looking.

I can't positively tell from the pictures, but there might be some white spotting along with the graying.

 

[Lankness]

From my test kit:
FC - 3.0
CC - 0.0
TC - 3.0
pH - 7.4
Alk - 40ppm
CH - 140ppm
CYA - 30

Looking back through my logs CH has always been 100-150 (I have only checked it 6 times in the year we've had the pool). Alkalinity was 220 the first time I checked it and was down to 60 within 2 months of the pool being filled the first time. It has been 40-60 since. CYA was 90-100 at the start, was down to 30 through last summer, spiked to 100 last Oct and has been down between 30-50 since.

That is all I can test with my kit...

The pictures from that other thread look really similar. We get calcium scale on the spillover from the spa that is a PITA to remove; it is solid white that typically builds on the grout lines. I can remove that with muriatic acid in a spray bottle and elbow grease - that's just pretty tough to do on the entire surface under the water.

If it is calcium scale building up everywhere - what is the solution? ScaleTec or something of that nature and hope that it resolves itself over 4-6 weeks?

Thanks.

 

[duraleigh]

Those test results would indicate calcium scaling as VERY unlikely.

I can understand it developing on the spillover from evaporation but your test kit results do not indicate calcium scaling at all. In fact, those numbers are pretty good.

 

[Lankness]

Those test results would indicate calcium scaling as VERY unlikely.

I can understand it developing on the spillover from evaporation but your test kit results do not indicate calcium scaling at all. In fact, those numbers are pretty good.

Hence my massive confusion in this. At this point I'm trying to get the builder to advise what it is, what caused it, how to get rid of it and how to prevent it. It's an uphill battle, but I don't want to do anything that would risk damaging the finish and/or them voiding the warranty.

Any thoughts on other tests to try? Metals to test for/have tested for?

Thanks for the response.

 

[Butterfly]

From my test kit:
FC - 3.0
CC - 0.0
TC - 3.0
pH - 7.4
Alk - 40ppm
CH - 140ppmCYA - 30

Looking back through my logs CH has always been 100-150 (I have only checked it 6 times in the year we've had the pool). Alkalinity was 220 the first time I checked it and was down to 60 within 2 months of the pool being filled the first time. It has been 40-60 since. CYA was 90-100 at the start, was down to 30 through last summer, spiked to 100 last Oct and has been down between 30-50 since.

That is all I can test with my kit...

The pictures from that other thread look really similar. We get calcium scale on the spillover from the spa that is a PITA to remove; it is solid white that typically builds on the grout lines. I can remove that with muriatic acid in a spray bottle and elbow grease - that's just pretty tough to do on the entire surface under the water.

If it is calcium scale building up everywhere - what is the solution? ScaleTec or something of that nature and hope that it resolves itself over 4-6 weeks?

Thanks.

Highlights above are mine.
Now, I know I'm tired and may be missing something, but why is the CH so low and why has it been kept so low? Recommended CH for plaster is 250 - 350.

 

[Lankness]

Highlights above are mine.
Now, I know I'm tired and may be missing something, but why is the CH so low and why has it been kept so low? Recommended CH for plaster is 250 - 350.

The water comes into our home through a water softener is the only reason I can say that it is low. I'm new to the pool game and was not aware of CH being low being a problem. When I've reviewed my logs with the builder in the past it was never brought up as a potential issue...so I'll readily admit I haven't worried about it.