Hi,

We build a SWG pool that was completed in June. We live in Austin and are loving the pool. But it's now 2+ months later and I am seeing some rust at the tile line. Our pool has concrete decking and coping, OK stone on the back wall, glass tile and a pebbletec alternative from CLI Industries. There is a water feature on the back wall.

We are only seeing the rust on the back wall. It's the only area with OK Stone and also where the water feature is located. The is rust on the wall near the water feature and also areas that are far from the water feature and seemingly dry. There are some small gaps between the concrete coping and the tile line. If there is rust, it does seem like it's more likely to be at a small gap. But lot of places with this small gap don't have the rust.

Here are some pictures:
http://twitpic.com/682siz <---- Here is a general look at the pool. Back wall on the left
http://twitpic.com/682ovj <-- rust example
http://twitpic.com/682ran <--- rust example
http://twitpic.com/682q26 <-- Shows the water feature. A bit of rust at the right

The PB said rust was to be expected and use a acid water mixture on it. We did this. The pictures are after a partial treatment. But I am now thinking something systematic is going on and needs to be addressed.

Any thoughts or ideas?

Thanks for reading!

Welcome to TFP

Sorry to here about your troubles. Given this is a fairly new pool, IMO rust stain like that are NOT to be expected. I'll let those in pool construction give expertise advice, but you have every right to doubt what you are being told. An ocasional acid wash won't hurt things, but if you will have to be dealing with that every few months, I would challenge the build quality/workmanship

My guess would be that the rust is coming from rebar or wire mesh that was used in the cantilever decking. The rebar or wire mesh should be in the middle of the deck and protected from corrosion. However, it is not uncommon for the rebar or wire mesh to be left at the bottom of the concrete where it will rust.

The rust normally does not infiltrate into the pool unless there is hydrostatic pressure causing water to flow under the deck and into the pool. Hydrostatic pressure is usually caused by poor drainage, especially when there is land nearby that is higher than the bottom of the deck.

Remedying the placement of the rebar would require the removal and replacement of the deck. Other than that, the options are to improve drainage and to seal the gap between the bottom of the deck and the top of the tile.

It's possible that the water feature could be leaking and that is the source of the water. If the water feature is the source, then you might see wetness near the rust when the fountain is on.

If the water feature is not leaking then you would usually only see wetness in the rusty areas when it rains or there is some other source of water, such as a sprinkler system.

James, that is great information. I can work on the drainage.



What would you use to seal the gap?

You can use a "non-sag" caulk, such as Vulkem 116 Non-Sag Polyurethane. Caulk comes in a variety of colors. Don't use a "self leveling" caulk because it will run.

It might be worthwhile to add a zinc anode to the bond wire to help reduce the rate of corrosion of the steel.