Greeting, passthebandaids.
Forgive me if i missed it, but how long had the pool sat that way before it came into your possession?
You may have a combo of organic and metal stains that are gonna be stubborn if scale is also in the mix.
Normally, your stains should have reacted to the chlorine puck or the vit C, but sometimes if there's some scale involved, it can take longer to get a reaction as the scale combines with the metal (eg and makes iron scale, for example).
In cases like those, its worth testing with dry acid (eg ph down) if you can get a reaction. If an acid test, so to speak, cleans it up, there is a tool you can buy to try an "acid wash" of sorts :
Amazon.com: Purity Pool UAW Underwater Acid Wash Set: Patio, Lawn Garden
In general, with really old organic stains, sometimes it will take chlorine, sun and time to remove.
So even though you've swapped out the water, in that case, I'd likely keep the FC right around slam level for a few days or weeks even to see if it lightens. You can still swim at just up to slam level, and since you're not losing FC to active organics, its not a huge outlay in cash.
The reason we usually want people to make the determination whether a stain is organic or metal is because slamming can sometime oxidize meals and tint your water. But in this case, given the sense that at least some of it appears to be organic, I think riding elevated FC levels would likely be in order. If it tints, then you can use some sequestrant later to put any metal back back into solution.
You may need to do both these things in tandem, eg. Fist run higher FC for a week, note changes, then try the underwater acid wash...or vice versa.
Another option is to try Jacks Stain ID kit and then proceed with whatever makes the stain react...slightly more expensive approach, but if the stain kit works then you know there is a specific stain remover to purchase that will work.
Here's a link:
Jack's Magic Stain ID Kit offered by Pool Geek
Hope that gves you some avenues to try.
If it were pure meals and iron in particular, an AA treatment might be worthwhile, but I'd hate to see you go to that trouble and have suboptimal effect. The vitamin c tells you how well the AA treatment might work and your results suggest tat it alone would not.
).
I am sorry these did not work.
