Empty pool, easiest way to get rid of metal stains?

[antoniosp]

So I had to empty my pool for PB could fix paint over a repaired crack and want to see what is the best/easiest way to remove the metal stains I have in my pool. Bit of history: I did the oxalic acid treatment while the pool was full, per instructions listed on site, but it didn't get rid of all the stains. In places/spots that I put the oxalic acid powder and let it sit on the stains they got removed but not everywhere else, despite lowering the FC to 0 and using 2 bottles of oxalic acid.
So no that it's empty I diluted some oxalic acid, took a small brush and started scrubbing on each rust/metal spot. they got removed after a few seconds of scrubbing but it will take day(s) if I was to do that in whole pool floor.
Question: Is there an easier/faster way to remove those stains now that pool is empty? I did try pouring some of the diluted oxalic acid on the floor and then used a large plastic broom to scrub but it didn't work, since metal stain spots are very small, sort of embedded on the textured pool floor and require direct scrubbing for 15-30 seconds for them to be removed. Any help is appreciated!
Here are links to pictures:
https://www.dropbox.com/s/632onqti8w2dc ... .52.34.jpg
https://www.dropbox.com/s/n6y32m8ln77qw ... .52.56.jpg
https://www.dropbox.com/s/fn1a621bcz1ti ... .53.13.jpg

 

[antoniosp]

So instead of continuing scrubbing, what I plan to do is fill the pool with just a couple of inches of water so the whole floor is covered with water and then put a whole box of Oxalic Acid in it so its super concentrated and hopefully will remove all stains. then I will empty it rinse it a bit and fill the pool again. Hopefully that will do the trick.

 

[antoniosp]

Since I am waiting for painted repair spot to dry out, I tried rubbing some spots with Muratic Acid and stains lifted up almost right away, I am wondering if I should use muratic acid instead when filling pool a few inches but I am concerned how many fumes that will cause and also how much muratic acid will be required. should I just stick with powdered oxalic acid?

 

[antoniosp]

So any advise before I head to the pool store and spend/waste money on this?