{Need Help} Yellow Staining Identification on white plaster - Algae/Scale/Stain?

clintwb

Member
Feb 10, 2021
22
Dallas, Texas
Pool Size
2400
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-3)
I have a 1 year old pool - Total DIY (Check out that thread here: Texas Dip Pool Build - DIY)
The past few weeks I have noticed that my plaster is not as white as it used to be. In fact I feel like there is some sort of staining/algae/scale problem. Because all of your pool wizards out there cant work without information, ill do my best to present some data here. Im new but ill do my best and get any other info you ask for that I can.

Pool Size: 2400 Gal
Plaster Type: SGM Durazzo Arctic White aggregate plaster finish

FC:8
TC:8.5
PH:7.5
TA:80
CH300
CYA42
Iron0
Copper0.1 ppm
Phosphates880 ppb
Salt2650

Here is a photo - the best I could get today. It LOOKS from the photo like the issue areas are lighter/white but in reality that is what it usually looks like and most of the plaster is currently looking a little yellow-ish.
IMG_5733.jpg


What I have tried:
-I have brushed (hard) about 10 times in the last week. Nothing really comes off.
-Due to my Sense & Dispense, my PH stays very stable, pretty close to 7.5, and occasionally dips down below 7 for a few Horus if it pumps a little too much acid in, but rarely goes above 7.8 (not sure I have seen/tested it above 7.8 once this summer).
-At one point my TA was low (about 40) but that lasted only about 1-2 days.
-Based on a handful of forums, I tried the vitamin C trick, let it sit on there for a while (5 min) and then brushed it away, no change

I am not sure what else to try. I cant quite figure out what it even is. It doesn't brush off, and high chlorine doesn't seem to do much (I spent a week with FC at about 9.5, then brought it down to 0 and back up to 7 and it has been around 7-8 for the past 2 weeks. --- The high FC is due to me attempting to understand the ORP sensor/control---- I KNOW, I KNOW... Ditch the ORP. I just want to TRY before I ditch it! :LOL: :LOL: :LOL:


Anyone have any thoughts on what to try next?
 
It really looks like iron staining.

Did you take the Vitamin C tablets, put them in a sock, crush them up a bit, and then set that on top of the stain for several minutes?
 
It really looks like iron staining.

Did you take the Vitamin C tablets, put them in a sock, crush them up a bit, and then set that on top of the stain for several minutes?
I just crushed them and placed them directly on a spot for about 5 minutes. And tried just rubbing one on as well sort of scraping it onto the plaster (I had not heard the sock idea) but it stayed in contact for about 5 min.

Iron level is 0.1ppm for what its worth.
 
I can't tell much from that photo. Perhaps a couple of more photos would help.
Ill see what I can do. Its sort of hard to get a good photo. The plater is usually quite bright white and now most of it is more off-white with a little yellow tint to it. The best photos I have been able to get have been of the few areas that are still white. Ill try today to post 4-5 more
 
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