Unfortunately, we do not recommend using CLR on pool tile. It could remove the finish from the tile. In addition, if CLR comes in contact with chlorine, it could result in toxic fumes.
Do not use CLR, petroleum, household cleaning products, or abrasive cleaners. Use only brushes that are approved for use on your vinyl liner. Suns effect on your liner: All pool liners installed by us are coated for protection against the fading effects of the sun, chemical absorption, algae, and mold.
Try a Commercial Cleaner or Professional
If the pumice stone did not remove the build-up, you can try a tile cleaner that contains sulfamic acid (CLR or Lime-Away). These types of cleaners are harsh and must be used with extreme care. They should not be used after you have added the regular pool chemicals to the water.
Calcium buildup is a white and scaly buildup caused by high pH or alkalinity levels in your pool water. This causes calcium carbonate to separate from the water and stick to the pool tile.
Clean Tiles with an Acid Solution. When using chemicals to clean your pool's tiles, you want to wear all the right protective clothing. Once you're suited up, you can then mix 1 gallon of water with 1 gallon of muriatic acid. When mixing, you want to slowly add the acid into the gallon of water.
All you need to do is heat a rag or a small towel in the microwave, pour vinegar on it and clean your pool tiles. Vinegar contains molecules that react with calcium to separate the deposition and eventually clean your pool tiles.
For light, thin calcium deposits, try using a soft brush (such as an old toothbrush) and a solution of vinegar and water. If that doesn't work, try cleaning the tile with a solution of water and muriatic acid (you can find muriatic acid at your local hardware or pool supply store).
Along with balancing the pH levels of your pool water, muriatic acid is strong enough to kill mold, remove rust stains, get rid of calcium deposits, and clean the surfaces of your pool.
Cleaning with a pumice stone takes a lot of time and effort. Depending on the amount of calcium build up this could take hours and hours over several weekends. And contrary to what your pool store or pumice packaging may say, pumice does scratch the tile surface.
Cleaning Tile and Grout with Muriatic Acid
Muriatic acid is extremely powerful, and using on tile and grout surfaces can permanently damage the areas you're trying to clean. Damage from muriatic acid can be so bad that the user may end up regrouting or replacing the tile.
Muriatic acid is a strong hydrochloric-based acid, that is a great descaler. Because of the intensity of this acid, it has the ability to remove severe lime and calcium deposits found in pools and toilets. However, because of the potency of this cleaner, it can cause damage to the eyes and any exposed skin.
In cases where your dirt and grime is only minimal, you can use homemade cleaners as such vinegar with water, baking soda and vinegar, toothpaste or even dish soap to remove the deposits. For tough stains or calcium silicate scaling, you'll need to clean the area using a pumice stone.
Acid should only be used as a last resort when cleaning tile. When all other attempts to remove stains have failed, a mixture of water and hydrochloric acid can be used to eat away at the stain and restore the tile's original appearance.
Kill Mold—Use muriatic acid to kill stubborn mold and mildew on hard surfaces, such as brick, tile, concrete, and stone. Mix one part muriatic acid to eights parts water, then spray or brush the solution onto the moldy area. Wait a few minutes, then scrub well with a nylon brush. Rinse the area well with clean water.
To remove soap scum and hard water deposits from a tile wall in a bathroom, mix one part muriatic acid with five parts water. Since muriatic acid is a harsh chemical, mix it outside. Follow the warning and instructions on the bottle, and be sure to wear rubber gloves and eye protection.
To protect the shine on your pool tiles once they've been cleaned, you should apply a clear coating to them. There are specially formulated waxes that can be purchased as pool care stores, and there are also chemical coatings that can be put on over your pool tiles.
Once media-blasting is complete, pool tile installations should be sealed, protected and regularly maintained per the other sections of this guide. NOTE: Always wear personal protection equipment, follow instructions for product use and protect surrounding surfaces when using cleaning or sealing products.
If you do add too much muriatic acid, your pH levels can dip dangerously low, and your pool water can cause rashes and eye irritation. Low levels of pH can also damage metals in your pool like ladders, railings, screws, bolts, and other important equipment.
We recommend adding Acid weekly! Adding a little and often is better for your water and can actually save you money overtime. Large doses over longer periods of time take a larger portion of your 'Total alkalinity' away.
Muriatic acid is also known as hydrochloric acid.
Cloudiness Due to Elevated pH
You may be able to clear the water by adding muriatic acid to lower the pH. Consult a table to determine the proper amount of acid to add to bring the pH from where it is to where it should be. Circulate the water for an hour, and then recheck the pH. Add more if needed.