Is this grout efflorescence? What to do?

[INeedaUsername]

Hi guys,

I'm seeing this white stuff pushing out of (and sometimes actually pushing out) the grout in the tiles that separate my spa from the pool. I don't see this happening anywhere else in the pool. It's very hard and not easy to scrape, suggesting it's not salt.

Any ideas what to do? What about the areas where the grout is pushed out? What kind of grout can I use?

In case it's needed, latest chemistry:
pH 8 (usual value)
Salt for SWG 2900 (came down with recent rain from about 3400)
Calcium hardness: 400
Alkalinity: 65
Cyanuric acid: 85

Thanks!

 

[duraleigh]

Welcome to the forum.

Yeah, that's efflorescence. You can remove it with muriatic acid after you scrape off as much as you can. Not much you can do about it unless you remove the water source behind the tile.

Your fairly high CH and TOO HIGH pH (keep pH in the 7's) are contributors to your issue.

 

[INeedaUsername]

Thanks, any suggestions on what grout to use to repair the tiles? Or does it not really matter?

 

[pooldv]

Any grout is fine to use. Looks like it is sanded grout.

 

[INeedaUsername]

Many thanks. I'm color blind, would you say it's a gray color?

 

[JoyfulNoise]

You can usually get grout color charts and sample comparators at any tile store that sells grout supplies. It would be best to get one of those so you can accurately match the grout color. Even being off by a single shade of gray can easily create an eye-sore. Also, measure your grout joint width - if it's 1/8" or less you use unsanded grout, >1/8" and you should use sanded grout. Also, there are two types of grout - cementious grout and epoxy grout. Epoxy grouts are better suited for wet environments like pools as they do not allow for water penetration BUT they are typically more expensive than cementious grouts and so I don't think PB's use it much unless it is specifically asked for.