Pool tile grout is used to repair or replace pool tiles. The primary factors in choosing a grout are the scale of the project and the desired appearance of the grout. A waterproof, sanded epoxy or cement pool tile grout will be suitable for most projects.
There are two main types of grout that are frequently used as pool tile grout: classic Portland cement grout and epoxy grout. Epoxy is harder than cement, is stain resistant, and is very durable. On the other hand, it is much more expensive than cement. Thus, for large-scale pool renovation or repairs, concrete grout is generally the most cost-friendly. For smaller, intermittent projects, however, epoxy grout may be the better choice as its shelf life is virtually unlimited.
When grouting a pool, it is important to choose a waterproof grout to maximize longevity; unlike most cases in which grout is used, pool tile grout spends most or all of its time underwater. While normal grouts will still work, they will not be as durable in those conditions. In general, epoxy grouts are naturally waterproof — cement grouts with that property are less common and are usually specialized grouts.
Another consideration when choosing a grout is the color. A well-kept pool often adds significant value to a property, but patchy tile grout can negatively impact the appearance. Since grout fades over time and can stain, it is very likely that grout used for simple repairs will result in a color mismatch with the original. The only way to totally avoid this problem is to perform a complete retile. Many stores that sell grout will have color swatches which can be used to match grout colors.
If the grouting project involves filling gaps larger than 1/4 inch (6.4 mm), it is probably best to use grout with sand added to it, which helps the grout holds more strongly. Pool tiles are often spaced farther apart than other tiling and may be set vertically — they will thus usually require sanded grout.
Finally, it is best to pick a pool tile grout with a setting time appropriate to the size of the project and the skills of the grouter. If the setting time is too short, it may be very difficult for a first-time grout user to complete a major project before the grout becomes too difficult to work with. However, more experienced users may be frustrated by extended grout setting times.