grey stains

misteur G · Jul 9, 2016

HI,

I have these weird grey spots which formed on the side wall of the pool (my pool is very light blue so I can easily see them). one is 1/1.5 inch big, the other are small , more like dots. I tried to brush them off but they don't go away. I just came back from 2 weeks vacation and have now some at the bottom of the pool.Any idea what it can be?

here are my chem info. I boosted my SWG while away just to make sure I will not get a bad surprise upon my return.
FC 15
CC0
FC 6
CC 0
Ph7.4
TA125
CH200
CYA 40 (that just dropped while away, I will readjust to 70)

kimkats · Jul 9, 2016

Have you tried rubbing a chlorine tablet on them? How about some crushed up Vit. C tablets? Those are my go to stain tests. BUT those are not like anything I have seen before.......what do they feel like? Can you feel them?

Kim:cat:

kadavis · Jul 9, 2016

May be cobalt bleeding through the surface. They use it in fiberglass pools and spas. Used to see it alot in the spas years ago, but most spa's are acrylic or some other composite now

misteur G · Jul 11, 2016

kadavis said:
May be cobalt bleeding through the surface. They use it in fiberglass pools and spas. Used to see it alot in the spas years ago, but most spa's are acrylic or some other composite now

After making some research, it looks exactly like cobalt bleeding...and there is apparently no cure for it...

kadavis · Jul 14, 2016

https://images-na.ssl-images-amazon.com/images/I/31P4p-iU8IL.jpg, this is the only product developed for this problem

misteur G · Jul 15, 2016

thank you Kadavis. I actually made some research and ordered it. it arrived last night. I will try it this weekend. DId you ever use it?

duraleigh · Jul 15, 2016

misteur G,

Please let the forum know if that stuff works. Cobalt is not very common but we have seen posts about it several times over the years. It will be nice to know that there is a fix.

misteur G · Jul 15, 2016

duraleigh said:
misteur G,

Please let the forum know if that stuff works. Cobalt is not very common but we have seen posts about it several times over the years. It will be nice to know that there is a fix.

Will do

misteur G · Jul 18, 2016

I haven't done the Cobalt cure yet, but most of the gray stains are gone.. the biggest on was just under the light and it totally disappear. I can find a 3 or 4 on some part of the wall but they are very tinny. this pool is full of surprises...