Stains

[Florida Dave]

I posted to this section because my pool store has recommended it is a chemical problem they can’t diagnose. I have 2 circular stains near the drains. The sides of the pool and parts of the bottom are darker like they are dirty. Standard chemistry tests and a test for metals (last year, sorry I can’t be more specific) have been normal. Does anyone have ideas? Thanks!

 

[Texas Splash]

Dave, first .. welcome to TFP! Here at this forum, we pride ourselves on assisting folks as much as we can, but also do so with reliable test results as more times than not, pool store testing is incorrect at best. So as a new member, the first thing we would recommend is obtaining either a TF-100 (link below) or a Taylor K-2006C test kit so we can see what your water results are like. I know, not the first thing you wanted to hear, but it's very important.

For stains, we need some history. How old is you plaster? Have you added any pool store chemicals to the water? Be honest! What about iron in your local water supply? On a well perhaps?

Finally, the first two things we generally recommend is to check a stain for is iron or organic staining. Try the following:
- Place a chlorine puck against the stained area for a few minutes. If it lightens, it's algae-related.
- Place some crushed vitamin C tablets in a nylon or similar material and lay it there for a few minutes. If it changes, it's iron.

Also, please update your signature with all of your pool info. It will help a lot later. Let's start there and do what we can. Welcome!

 

[Florida Dave]

The stains were present when I bought the house one year ago. The plaster is most likely original (12 years). We have city water and there is no iron. I did rub vit C and a chlorine tab against the stains and it did not change them. When we first moved in, I had to add stabilizer and muriatic acid but everything has been stable stable since then. I will check out the test kits. Thanks!

 

[Texas Splash]

You're welcome. When you do post a set of results, it will be real-time, so we won't have all the years of history form the previous owners to know if there are any calcium issues (historically high or low) to factor in, but it should give us an idea. Let us know how things turn-out or if you have any more questions.

 

[Florida Dave]

Update: I have not done the chemical testing yet. However, I had a local guy over (thinking about replacing some equipment) and he thought the two circular stains were from chlorine tabs being dropped into the pool. This scenario fits as the house was vacant for some time. I will continue to update as I get results.