You come out to the patio in the morning on a good weather day, sipping on your cup of coffee, look down, and notice there is a chalky substance all over your pool deck. I have this same issue, especially during the spring months when Las Vegas actually gets a little bit of rain and humidity. So, what exactly is it?
The chalky substance commonly found on a pool deck is called efflorescence. Efflorescence is a crystalline, chalk-like salt deposit that is caused by leftover water-soluble salts after evaporation. Efflorescence is most common on brick, stucco, concrete, and natural stone.
Why Efflorescence Forms
Efflorescence is a natural phenomenon that varies in size and appearance. depending on a factor like geographical location, type of masonry, and the chemical makeup of the water.
Efflorescence can occur when water-soluble salts are present and moisture is available to allow those salts to dissolve. Once the salts dissolve, the new saltwater solution will then evaporate. The remaining salts leftover then crystalize and form into a chalk-like material known as efflorescence. This is why it is a more prevalent issue in pool systems with a salt-cell or in areas with high humidity.
The formation of efflorescence, specifically on a pool deck can be attributed to a few things:
- Improper or lack of a deck sealer
- A poor quality deck sealer
- Clogged channel drains
- Improper slope angles
Efflorescence can be largely seasonal and be more prevalent in winter and spring due to the increased amounts of rain and snow. That being said it can still pop up in the summer, or dry climate locations.
Efflorescence in itself isn’t dangerous. If it is left untreated for long periods of time it may seep into your deck and, through osmosis, cause flaking and cracking issues that may be very costly to repair. If you notice efflorescence you may want to take action.
4 Ways to Remove Efflorescence
You may have tried to go over the spots with a hose and it seems to have disappeared only for it to reappear the next day. The outer film of the efflorescence is usually what appears as white and it becomes transparent when water hits it. You will need to apply some elbow grease in order to remove the deposits completely.
It is important that the methods outlined be completed on a dry and warm day, and do not use the pool so that decking has time to dry completely.
1. Hand Washing – A stiff brush and a mild detergent with warm water can do wonders to remove the efflorescence from your deck. Diluted vinegar can also work if it is a small area. Once you’ve brushed your deck rinse it thoroughly and pat it down with a towel.
2. Pressure Washing – Using a pressure washer can easily dissolve the efflorescence. Ensure that you use a pressure setting just high enough to remove the efflorescence and dissolve the crystalline structures. Too high of pressure can chip the deck and open pores in the concrete, and lead to efflorescence reforming, so take care when using a high PSI unit, or shop around for a pressure washer that is rated around or below 2000 PSI to be safe.
3. Chemical Cleaning – For some extreme cases, chemicals may be needed in order to adequately remove efflorescence. Gentler methods like hand washing and pressure washing should always be attempted before using chemicals. There are efflorescence cleaners available for purchase, like this cleaner on Amazon, that can assist in the removal. The directions to use the cleaners should be adhered to strictly and use personal protective equipment (PPE) like gloves and goggles.
4. Sand Blasting – abrasion cleaning like sandblasting can be very effective at removing stubborn efflorescence. This method should be a last resort as the abrasion can cause damage to your pool deck and the deck may need to be resurfaced when completed.
All of these methods are great DIY solutions if you have the time and the know-how. It is best to consult with a concrete contractor and/or a pressure-washing contractor in order to get the best advice for your unique circumstances.
If you’re not up to do it yourself there are plenty of companies that can handle efflorescence. I contacted 2 respected local pressure washing companies in my area (Las Vegas). For pressure washing my pool deck and patio, I was quoted $145 and $165 for a 25ft x 55ft area.
How To Prevent Efflorescence
There are some simple things that can be done in order to ward away the formation of efflorescence in the first place.
Hydrophobic Sealer – Resealing your pool deck with a hydrophobic sealer can reduce the absorption rate of water into the deck. This can reduce the frequency that efflorescence occurs.
Clear Water Repellents – These repellents use a water-based Silane-Siloxane mixture that chemically adheres to masonry surfaces allowing the rainwater, or pool water, to sit on the surface of the pool deck. These repellents also have the benefit of slowing the deterioration of the deck material. Water-based repellents are recommended because they are non-flammable and easy to clean up after application.
Manually Dry the Deck – If you are having an extra splashy day with the kids or pets and the deck is covered in water, it may not be a bad idea to grab an extra towel or two and shimmy around the deck soaking up the water. Be sure all pool floats and pool toys are dried off as well. Any runoff from wherever you may store them can puddle as well, especially floats that have drink holders.
Re-establish The Deck Slope – In general pool decks should slope about one-quarter inch per foot away from the pool and away from your home. This pitch can weather over time and can cause puddles. In which case, you may want to correct the slope by installing a cement-based overlay. If your pool deck is made of pavers, simply removing the pavers and correcting the pitch can help.
Check the Pool Drainage System – Over time debris can work its way into the drain channels of a pool causing a blockage. These drains are usually easy to pry off and cleaned similar to how you would clean a gutter. Pool drainage servicing may be included in your pool service contract if you do not maintain the pool yourself, check your service contract to see if it’s included.
Efflorescence cleaning is more treatment rather than a cure. Efflorescence is likely to keep occurring unless the moisture-causing issue is alleviated. It’s best to keep control of it to ensure the lifespan of your deck and reduce the frequency of costly repairs. In general, a homeowner can handle this issue on their own using a little elbow grease, a brush, and detergent.
Contributing factors like slope and weather conditions such as rain, snow, sleet, and humidity can be mitigated by properly maintained drainage systems and drying your pool deck after use or once the weather clears up.
If you are using a service in order to remove efflorescent and/or reseal your pool deck, be sure to check references and pictures of completed projects. There is a multitude of websites that you can use to compare and select the professional that fits your needs and budget. Yelp, Google Reviews, Angie’s List, and Home Advisor are my top recommendations to start.
Why does my dog keep licking my pool deck?
Besides being thirsty and licking up pool water, some dogs tend to enjoy licking efflorescence. Efflorescence is salty in taste because it is typically a mixture of salt and calcium. Both of which are safe to ingest but still may cause your pup to have an upset belly (consult your veterinarian for the most up-to-date information).
Can I paint over top of efflorescence?
No, efflorescence should be cleaned and the surface should be dried prior to painting or resealing. Painting over efflorescence can cause the paint to chip, crack, and fade over time.
Can efflorescence spread?
Water can wick through masonry over a six-mile radius. Once this water travels through efflorescence it can carry the salt deposits to unaffected areas and spread if left untreated.
What happens if efflorescence is left untreated?
Mild efflorescence may go away on its own. The salt deposits are water-soluble and so rain or snowfall may be enough to dissolve it away. This is generally okay if your area gets very consistent precipitation but take caution to to the warnings outlined above.