Corrosion on exterior wall bottom on Saltwater 8k pool?

[Kevin-S]

Hi, I noticed this around the base of the exterior of the wall on my Saltwater 8000 pool. Pool has completed two great seasons, just starting its third. Wondering what these 'bumps' are. I have stone surrounding my pool, just a thin layer right next to the pool with a little landscape fabric to stop any scratches. I have a pic with the stone pulled away, and one without the stone disturbed, you can it gets air where some of this is, and no fabric laying over it. When I rub at it, there is no signs of rust behind it, and seems solid. It is only at the base of the wall, right behind that stone. Some form of corrosion? Is this a problem/something to worry about? or just something that happens.
This pool model is coated in a corrosion resistant paint and also rated for semi-inground installation (mine is not inground, only have enough dirt at the base to cover the base rail per my installers instructions.)

I plan on contacting the manufacturer if there is any issue or doubt here.
Thanks!

 

[Bperry]

Hi, I noticed this around the base of the exterior of the wall on my Saltwater 8000 pool. Pool has completed two great seasons, just starting its third. Wondering what these 'bumps' are. I have stone surrounding my pool, just a thin layer right next to the pool with a little landscape fabric to stop any scratches. I have a pic with the stone pulled away, and one without the stone disturbed, you can it gets air where some of this is, and no fabric laying over it. When I rub at it, there is no signs of rust behind it, and seems solid. It is only at the base of the wall, right behind that stone. Some form of corrosion? Is this a problem/something to worry about? or just something that happens.
This pool model is coated in a corrosion resistant paint and also rated for semi-inground installation (mine is not inground, only have enough dirt at the base to cover the base rail per my installers instructions.)

I plan on contacting the manufacturer if there is any issue or doubt here.
Thanks!
View attachment 568469View attachment 568468

Its rust.

 

[Kevin-S]

Maybe I should add the brown on the wall in the pic without stone is dirt. The raised dots are white/color of the paint. Scratching at them doesn't reveal rust under them that is typical with rust, at least so far. It appears to be at the base the whole way around the pool.

 

[Kevin-S]

To follow up: I submitted a question to thepoolfactory about this and sent them pics. They were very quick to call me. They say the acidity in the rocks can cause corrosion on the wall, and fortunately I caught it early enough to fix it before its a bigger problem. They recommend pulling the stone back, cleaning the bottom of the wall, then coat the corroded part of the wall w/ rustoleum or similar. Then using tar paper as a barrier between the stone and pool wall.

 

[JoyfulNoise]

Rocks are not “acidic” Once again, pool industry for the win with the most idiotic analysis on the interwebs …

But yes, I would pull back all the rocks and soil, brush the loose paint and any rust off using a brass brush (not steel!), and then coat with a good quality anti-corrosion paint.

Reduce contact with moisture as much as possible.

 

[phonedave]

Rocks are not “acidic” Once again, pool industry for the win with the most idiotic analysis on the interwebs …

I read that and was amazed that the pool store had a geological analysis lab and geologist on staff. There are rocks that CAN be acidic. Or more accurately, as water runs over them they leach out minerals that will reduce the pH of that water. There are rocks that will do the opposite as well - raise the pH.

But for the pool company to make this call, and for them to blame the corrosion on this effect, is pretty impressive to do over an email picture.