Concrete Color Stains Covering The Walls And Floor

[tkalla2000]

Hello, I got a call from a lady yesterday, with a pool that is staining real bad. I went over and checked it out, and this is what I found. The pool pretty much looked like a 20 year old pool, where the plaster gets thin and the concrete starts appearing. I took a knife and made a small scratch in one of the stains and there is bright white new plaster behind the stain. This pool was built in 2008. She said about 9 months after it was built, it started to model. In march of this year a company came out, drained the pool and sanded down a layer of plaster and acid washed the pool. She says within 3 weeks after that the stains started to appear. She said the stains got noticeably worse day by day. I'm not sure how long the chemistry has been out of wack, but when I tested yesterday, it was way out of range.

FC = 4.0

PH = 6.8

TA = 30

CYA = 60

CH = I ran out of drops at 450

TEMP = 93F

I know the company that does weekly maintenance on the pool was there on Monday, so I'm thinking that the PH was high due to the SWG and maybe they put a little to much acid in to give me that very low reading. My only guess with the calcium being so high is, maybe there was allot of plaster dust still in the pool when they filled it up, and maybe they initially raised the chlorine using cal hypo. I put a bottle of Jacks Magic in the pool yesterday and I will be going back tomorrow to adjust the chemistry. I have never seen a staining problem this bad. She was talking about re-plastering the pool, but I think the stains can be removed with chemicals. If anyone has any idea how this could happen and how it can be fixed, I would greatly appreciate some help.

[quantumchromodynamics]

When your pH is outside of the normal test ranges, you need the Long-range pH test kit as shown Here

Your carbonate alkalinity is near zero.

Aggressive (Negative Saturation Index) pool water will leach calcium hydroxide and calcium carbonate out of plaster. Anytime the Saturation Index is negative, the plaster will always be dissolved.

In my opinion, in many cases, gray discoloration is caused by one or more of the following causes:

1) Workers sometimes use accelerants, such as calcium chloride, to speed up the plaster cure rate. In most cases, calcium chloride is not necessary, but is used primarily by impatient or rushed workers. The calcium chloride can cause discolorations in the white plaster. If calcium chloride is not of high quality and added consistently and properly, it will cause color variations.

2) If the plasterers use regular steel, aluminum, magnesium or other metal trowels that are not certified as "No-burn" trowels (Usually chrome plated or high quality stainless), the metals can be transferred to the plaster through friction.

3) If the workers allow the plaster to get too hard and they have to overwork the plaster. The use of accelerants increases the risk of the plaster setting too fast. If the work is done on a very hot day, and there are not enough workers to trowel the plaster, then the workers will not be able to keep up. Hard­trowelling reduces the water to cement ratio, which cause the plaster to become dark.

Can you provide the flowing test results:

Calcium

Salt (Not TDS, but actual chloride titration test)

Total dissolved solids

Iron

Copper

Here is a link to the National plasterer's Council "ASK US A QUESTION" page.

This could be from Calcium Silicate Hydration, which is caused by calcium hydroxide that is not brushed from the plaster surface. Over time, the calcium hydroxide is converted to Calcium Silicate.

"CALCIUM SILICATE HYDRATION (MOTTLING)

This usually starts to be noticed at about 3 months and can be seen best when the pool is in shade (Mornings, Evenings, and Cloudy Days). At 3 months, you see it, but cannot really point your finger at it. At 4 or 5 months, you will say it is in that area over there. By 6 or 7 months, you will not need to point it out because it is apparent."

http://www.magic-technologies.com/pdf/remedies.pdf

[tkalla2000]

Thanks so much for the info. I have not yet had a chance to test for metals. However the home owner told me that the company that sanded off a layer of plaster was using metal sanding discs. The pool started showing these dark stains in the first 2 weeks after the sanding. I will be going back to this pool tomorrow, does anyone know of a good product to remove these stains?