Yellow Stain New Pool

[BPet]

Ever since the pool was filled, 2 months ago, I noticed yellow patches where the floors meet the walls and in corners and other areas. I can only see it in the morning or at night when there not too much sun. I mentioned it to the pool builder and the only way they could remove it was to use a metal wire brush. When I looked with goggles, it looked to me like the area had not been worked enough when the plaster material was applied and so you can not see the flecks of colored aggregate as much as you can in other areas - so you see more of the white plaster on the surface which appears yellowish and has a slightly different texture. Has anyone ever hear of this? There are some more areas that the pool builder did not fix and I was debating on whether I should use a metal bristle brush or try pumice stone? When I checked with goggles after the metal brush was used - the surface was no longer yellowish - but it seemed to me like it was a little darker than the rest of the pool - I wonder if the metal in the brush had anything to do with that?

The chemicals in the pool look good - although the PH is running high and so I'm getting a handle on that - just got the TFTestKit yesterday - I have 3 copper Scupper water falls...so aeration may be the culprit to the high PH.

Thanks for your input on how best to deal with the yellowish areas...

 

[Texas Splash]

Well, it's good you have the TF-100. I would first recommend posting a full set of test results for us (FC, CC, CYA, pH, TA, and CH). From there we can try to determine if it is a pool/plaster issue, or possibly related to mustard algae which can form in shaded areas of the pool against the walls, etc. Pool School - Mustard Algae

So post some test results and we'll what we can do for you.

 

[BPet]

FC - 11 (just turned chlorinator down to 10% today and will check daily - it was at 50% but I run pump for 17 hours a day because I like to look at water features)
CC - 0
CYA - 70
pH - 8.2 (added Acid today)
TA - 80
CH - 325
Salt - 3600 (Intellichlor suggests 3400)

Thanks,
Brett

 

[Texas Splash]

Brett, looking at those numbers as they stand right there, aside from the high pH which you already addressed and running a little strong on FC, those are good numbers. I guess we have to ask our self a few questions now:
- Has the FC always been running this strong? If so, it would be odd to have any algae growing
- If you still wanted to confirm no algae, you could do an OCLT tonight (with chlorinator off after dark) to see if FC drops more than 1 ppm before the sun hits the pool in the morning. I doubt it will, but you can check.
- If algae is ruled-out, and it may be in your case, that would bring us back to the plaster itself and how it was applied/cured.
- Just curious .. In Wellington, does your water have metals in it (iron or copper for example)? Filled from a well?
The plaster is a bit out of my league Brett, so I'm going to have to see if some other members have had experience with that one. I'm very curious to see how your situation turns-out.

 

[BPet]

Texas Splash, thanks for the response. For the first month, the builder used regular chlorine to maintain chlorine levels, then they installed the Salt Water Chlorinator. It has been high ever since I have been testing it - which was after the first month (the pool builder maintained it for that first month). When they applied the plaster, it rained in the middle - they tented the pool and continued working - not sure if that matters? I am not aware of having metals in the water? - we have county water - not a well and so I would guess that it does not have metals?

When I look very closely at the discolored areas with goggles, the plaster looks different than the surrounding areas and so I would guess that it's not algae - but I'm not an expert on plaster. If I look at the pool from the second story of the home, should the surface of the plaster look even throughout the pool or is it normal to have variation in areas - it is not enough variation to see in the bright sun - but if the sun is down I can see it...I would not mind scrubbing the entire surface of the pool with pumice or some other substance if that was the cure to having a uniform surface - but I don't want to do more harm than good and so hopefully a plaster expert will respond

 

[BPet]

Just had Pinch A Penny test the water for Metals - they indicate there is no copper or iron present. They also indicated my Chlorine level is 4PPM. I tested it when I got home and the basic test indicates 5+ and the more detailed test indicates 8.5PPM - so I'm not sure how accurate their metal test is either?