There’s a reason why Sukabumi pool stone tile is a prime choice for five-star resorts around the world. When dry, it has the look of a classic grey natural stone used in backyard and landscape applications. But once submerged, it lights up the water with radiant teal, transforming your outdoor space into a tropical lagoon. This effect comes from the stone’s natural composition. Formed from volcanic activity deep beneath Indonesia, Sukabumi, also known as Pedra Hijau, Indonesia Green Stone, or Bali Stone, is an igneous rock with fine pores and a unique mix of green volcanic minerals. When water fills those pores, light reflects differently, creating its signature color. Island Stone & Tile has been a leader in bringing Sukabumi to the U.S. market. The Sukabumi Select collection includes mosaics and tiles in a range of sizes suitable for pool interiors, waterlines, coping, decking, and more. Island Stone & Tile Director of Technical Services, David Fatula, answers common questions about natural stone pool tile installation.  Tropical backyard pool featuring Sukabumi natural stone tile What do people most commonly get wrong or misunderstand about Sukabumi natural stone pool tile before they install it? Sukabumi is often mistaken for marble, but it’s not. It’s closer to a dense limestone or granitic stone. Many green marbles and serpentines are moisture-sensitive and require special adhesives to prevent warping. Sukabumi does not have this issue and can be installed with modified thinset, making it ideal for pool applications. What's the most common maintenance mistake people make, and what should they be doing instead? A common mistake people make is waiting to seal it. Once a job is complete, there’s a period before a pool fills, and people often let the stone sit and seal it right before they fill it. It’s beneficial to seal the stone right after installation, because there can be tiny pieces of iron in it that you can’t see, but can cause a slight reddish undertone. When you seal the stone, you reduce moisture absorption, which helps prevent the appearance of that undertone. If we see a big iron deposit in our manufacturing process, we will cull that out. Another mistake would be regularly cleaning the stone with acid. With polished stone, the minute you put acid on, it strips the polish. Sukabumi has a honed finish, so if you were to get a little bit of acid on the stone, it shouldn’t be a problem. But if you regularly clean any natural stone – even with a honed finish – with acid, it will begin to degrade the surface. The stronger the acid, the more quickly that happens. Outdoor pool with Sukabumi stone tile finish What other recommendations do you have regarding sealing? When you use penetrating sealers (or “natural-look sealers”), it generally won’t change the look of the stone. They’re absorbed into the stone’s top layer, reducing the risk of staining and moisture absorption. That being said, with a natural-look sealer, since it’s not going to absorb that moisture, you’re not going to see that deep color change that Sukabumi is known for. If you really want that rich color, consider an enhancing sealer, which brings out the stone's natural color. The way to simulate what it will look like when enhanced is to get it wet. Often when they’re selling stone in showrooms, they’ll have a little spray bottle or a sponge, and they’ll wet the stone to show you what it looks like. We recommend sealing all our natural stone products when installed in a pool, and that’s slightly counter to what you hear in the pool industry. A lot of tile installers ask, “Why seal the stone if it’s going to be submerged? Will I even be able to seal it again? Would I need to drain the pool?” The answer is no. At some point, you need to drain your pool and replace the water anyway, because it tends to go bad. The water no longer holds the minerals in suspension, so the proper thing to do from a maintenance perspective is to drain and refill the pool. That’s the time to reseal it. If you have an all-tile pool, it’s certainly possible to drop the water level a little and reseal the waterline without draining the whole pool. If the water is kept in balance and the stone is properly cleaned, it should hold up well over time. What really causes a sealer to lose performance is when it’s worn away by scrubbing, foot traffic, or other surface agitation. That doesn’t happen in a pool below the waterline in the same way it does on a kitchen floor or a shower wall, where you’re cleaning it regularly. How does the honed finish affect the feel underfoot and the ease of cleaning? One reason we hone it is to increase the dynamic coefficient of friction, which is a fancy way of saying “how slippery the surface is.” Obviously, if you’re going to put the Sukabumi on a beach entrance or steps down into a pool, you don’t want it to be slippery. By honing it, we’re significantly increasing its slip resistance, and it feels nice underfoot as well. Sometimes, when you’re on a really shiny, highly polished surface, it doesn’t feel as comfortable as when you’re on a honed or matte finish, which has a little more texture. It makes you feel more stable when you’re standing on it. The texture of a honed finish tends to hold on to a little more of the greases and oils that come off our bodies, and collects on the waterline, which can easily be removed with a nylon scrub brush and the appropriate cleaner. The standard tile industry recommendation is to use a pH-neutral or slightly alkaline cleaner for natural stone. Backyard in-ground pool featuring Sukabumi natural stone tile What pool chemistry or water-treatment factors should homeowners know to protect the stone? In pool chemistry, there are three types of water: in-balance, corrosive, and scaling. In-balance water generally has a pH between 7.4 and 7.6. Scaling water contains high levels of dissolved solids, and as moisture evaporates, it can leave behind mineral deposits, causing a white, chalky buildup on the surface. Corrosive water is too acidic and can degrade the grout, stone surfaces, and any metal hardware in the pool. Generally speaking, you want your pool to have in-balance water. Is Sukabumi appropriate for spa/hot tub applications as well, or is it strictly for pools? Yes, it can be installed in a spa or a hot tub in addition to a pool. Those are not dynamically different applications. We’re talking about a 30- or 40-degree temperature shift, and that won’t have a significant impact on the stone's performance. Sukabumi natural stone pool tile collection What size and format do you most often specify, and why? The 1.25-by-1.25-inch mosaics, available sheeted, are a really good choice for pools with curves. You can’t follow a radius or a curve with a 4x8 or a 6x6 tile as easily as you can with a mosaic. The 6-by-6 is a really popular waterline tile. But a lot of people want more than just a waterline of Sukabumi in their pool, because they want to see some of it underwater, where it becomes really dynamic. When Sukabumi comes out of the box and it’s dry, it has a light to mid-green tone, but when you get it wet, it develops this rich, dark green color, and it’s spectacular. That’s why it’s becoming so popular. It’s been popular in the Pacific Rim for many years, and now it’s catching on in the U.S. How does Island Stone & Tile hand-select the stone? What are you looking for in terms of tone and variation? We don’t want all the stone to be a light or dark shade. We want a range of shades because that’s what gives you nice variation. We don’t want to see deposits of iron or compressed clay. Occasionally, you’ll see a little pit in the surface of the stone due to compressed clay being present when it was formed. When we see those deposits, we will cull those pieces out, because eventually, especially if it’s exposed to moisture, it will dissolve, and then you’ll have a pit in your stone. You may get a piece here or there that has a lot of high and low spots, or a pitted surface from other causes during its formation, and we’ll cull those out, too. Honestly, some manufacturers will take whatever comes in, cut it, shape it, and box it up. We’re more selective with our stone. We dictate to the quarry what we want, they take a first pass at quality control, and then we’ll do a second one when we receive the stone to remove the pieces that don’t meet our standard. Let Island Stone & Tile Help If you have any further questions about whether Sukabumi is right for your project, contact us today to consult one of our staff experts. You can also request samples of our materials or view them at a showroom near you. For additional information, read our Sukabumi Collection Spec Sheet and the Natural Stone Tile section of our FAQs page.