Dots on pool steps, plus metal/rust stain questions

kimbernw

New member
Jun 26, 2021
2
Oklahoma
Earlier this summer we had the concrete deck around our fiberglass pool redone. The workers dropped some metal parts in the pool, causing some rust stains on the bottom (picture of one stain attached). To try to fix it, I dumped ascorbic acid in the pool, followed by Metal Free (or something similar) per the directions. It did nothing for the rust stains, and a few days later the entire pool surface turned yellow. We realized that was an overall metal stain, so we did cycle after cycle of ascorbic acid (which did work on that overall yellow staining) plus sequestrant, but the staining kept coming back. At one point I also bought a CuLator bag for the skimmer (not sure that did anything, though) and did a couple rounds of adding cellulose fiber to the skimmers and cleaning the filter a couple days later (both times we did that the filters/fiber were orange from the metal staining). We have that issue mostly under control now (though I do sometimes still see a small bit of overall yellow staining), but throughout that process I started noticing these dots on the pool steps (pictures attached). They look like rust dots. The Leslie's guy told me they look like black algae, but they're reddish and I just don't think that's correct. Any thoughts on what they are? Is there anything I can do for them and/or the bigger rust stains on the bottom? I've rubbed Vitamin C tablets and chlorine tabs on the small dots with no success, and I've also tried resting a sock filled with ascorbic acid on the larger stains with no success. Any help would be so appreciated!!!
 

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Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2014
32,954
Texas, San Antonio/Marion, South-Central Area
Pool Size
17888
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
Welcome to TFP! :wave: For rust stains, the Vitamin C and ascorbic acid should work. Had you tried rubbing a Vitamin C tab directly on teh surface to ensure good contact?

For the spots, any chance something locally or from the yard got blown-in? Yard work, fertilizer perhaps?
 

kimbernw

New member
Jun 26, 2021
2
Oklahoma
Unfortunately the rust stains are too deep to be able to rub a Vitamin C tab on. Is there a good method for doing something like that in the deep end? Perhaps I just need to be more patient/persistent with the ascorbic acid/sock method? Yes, there's a chance something could have blown in on the steps...we had fertilizer applied to our lawn a few months ago. Any remedies for that? Thank you!!
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2014
32,954
Texas, San Antonio/Marion, South-Central Area
Pool Size
17888
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
Many fertilizers have iron in them which can produce that shotgun pattern of iron spotting. You can try placing a bunch of crushed Vitamin C tabs in a thin nylon which might touch the surface better. Drop in the water and hold against an area with the brush pole.
 
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