May 9, 2020
Hello all, rainy day here in MD, so instead of swimming in the pool, I’m thinking about cleaning some stains!

We bought the house in October and opened the pool in early May. Some of these stains have been around since we opened (and we noticed some of them even when we looked at the house last fall), although they appear to have maybe darkened a bit. Other stains, like the one along the base of the wall in the deep end, seem to have developed since we opened.

I’ve been working from home this summer, like many others, and have been able to keep careful watch on chemicals. I’ve also vacuumed and brushed pretty regularly. Using bleach as my sanitizer. The only other chemical I’ve added since opening the pool is muriatic acid to knock the pH down a bit.

I did try the vitamin C tablet test on several of the stains, and it definitely seemed to lighten or remove some of them, although the ones that lightened have sort of darkened again since doing the test. So I’m considering doing a full ascorbic acid treatment. The downside of that seems to be that it’ll put the pool out of commission for at least a few days, and the kids wouldn’t be too happy about that!

Anyway, below are my latest test results and some pictures of the stains. They’re not really noticeable when it’s sunny and the water is sparkling, but otherwise they’re kind of annoying.

I guess my question is whether to do the ascorbic acid treatment or anything else, or perhaps wait until the end of the season. Welcome any thoughts!

FC 7.5

CC 0

pH 7.8

TA 80

CH 280

CYA 40

Temp 84



Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
Laughlin, NV
If it was iron, vitamin C would have cleaned it up immediately.

Copper. Any products now or in the past with copper in them?


May 9, 2020
Definitely no products with copper since I took over the pool in early May. Only bleach and muriatic acid. But the pool is about 9-10 years old, so who knows before we took ownership.

The vitamin C definitely lifted a couple stains completely or nearly completely - two on the steps for instance. But for other stains, it only seemed to lighten them temporarily. Perhaps a mixture of copper and iron staining? Should I try the Jack’s Magic kit?