Pool mystery stains

Jul 26, 2016
57
Little Elm, TX
Over the weekend I drained my pool completely, had it acid washed, and refilled it on Monday. On Tuesday, I started noticing some stains which have gotten bigger and darker today. I haven't tested the pool water yet today because I'm in process of cleaning the filter cartridges (they were full of muck and currently soaking in a cleaning solution) but here it is for the last 2 days-

DateFCCCCYApH
7/25/20169.5041 ppm7.4
7/26/20164.5035 ppm7.6

Any ideas on how to fix it? More chlorine? More acid?

View attachment 52634View attachment 52635
 
I'm having a hard time seeing the stains, although in the lower pic I do see an area of "speckled black dots". Is that what you are referring to? Since you just had the pool washed and it was clear before filling with new water, my gut tells me you have some metals in the water that may be contributing to this new staining. Even though it's city water, weird things happen at the source. You might want to have a fresh (non-chlorinated) sample tested at the pool store just to see. You could also try the following:
- Try vitamin C on it. Regular tablets crushed in a sock or nylon will do. If it lifts the stain it was probably iron. If it made the stain darker, it could be copper (i.e. from algaecides) in which case try some dry acid on the same area.
- Try a tri-chlor puck on the area to see if it's organic. If that works, then an increased FC level may help reduce the overall appearance of the stain.
- There are also over-the-counter methods to ID a stain (i.e. Jack’s Magic Stain ID Kit – about $15) that can be used to help identify the cause of a stain.

Let us know if any of this helps or you see anymore changes.
 
No, if it is organic stains then rubbing a trichlor puck on it will lighten the stain answer maintaining elevated chlorine levels and brushing daily will slowly remove them. FC should be around 50% of shock level for your CYA, [FC/CYA][/FC/CYA] and could take a week or two depending on the stain and how long it has been there.
 
Identify the stain before you can fix it.

An organic stain will lighten if you place a trichlor puck on it for a few minutes.

An iron stain will lighten or disappear if you crush up vitamin C tablets, put them in a sock, and hold it down on the stain for several minutes.

Report back.
 
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