black streaks on 3m plaster surface

[trump]

my pool has black stains on the walls and all chem are fine could this be caused by electrolysis from not bonding the salt system?

[Guest]

my pool has black stains on the walls and all chem are fine could this be caused by electrolysis from not bonding the salt system?

[mr_clean]

black streaks on 3m plaster surface
my pool has black stains on the walls and all chem are fine could this be caused by electrolysis from not bonding the salt system?

can you give chemical readings?
FC-free chlorine
TC-total chlorine
CC-combined chlorine
PH-reading
TA-reading
CH-hardness
CYA-conditioner
Have you had water tested for metal/minerals?
are black stains only on walls or floor also?
what color is 3M?
do you fill pool with well-water?

[trump]

3m color is blue
ph 7.4
chlor 3.0
free chlor 3.0
cy acid 100
tds 2500
hardens 800
some stains on bottom but spa has no stains

[Guest]

3m color is blue
ph 7.4
chlor 3.0
free chlor 3.0
cy acid 100
tds 2500
hardens 800
some stains on bottom but spa has no stains

[mr_clean]

3m color is blue
ph 7.4
chlor 3.0
free chlor 3.0
cy acid 100
tds 2500
hardens 800
some stains on bottom but spa has no stains

I think you probably have staining problem from metals in water. You can take a sample to pool store & have them check it.
Your hardness level is 800 which should be 150-400, draining some water & refilling until you get there will do it.


you can take a white sock & add 1-lb PH decreaser & let it sit on a stain for 15mins & if it starts to come off it's metals.
using a bottle of sequestering agent/metal-remover after lowering hardness & using as preventative will help for future.
To get stains out you would need to lower PH to 6.8-6.5 for a couple days & scrub stains as much as possible until gone. Then readjust PH.

If stain does not start to come off then it would be black-algae & you could take a chlorine tab & rub it on a spot & let in sit on it for 1hr. If it comes off then BA.

The only time I have seen electrolysis problem, is people with pools next to under-ground electrical lines next to yard & its not black but a light gray & looks like a spider web in plaster not on outside of it.