Best Types of Salt for Pools (and What to Avoid)
When you own a saltwater pool, salt is the essential ingredient that your Saltwater Chlorine Generator (SWCG) uses to keep your water sanitized. But a common question new owners have is, "Can I just use any salt?" The answer is a definitive no. Using the wrong type of salt can lead to stained pool surfaces, cloudy water, and even damage to your expensive salt cell. This guide will explain exactly what to look for when buying pool salt and which common types of salt you should absolutely avoid.
Before you purchase salt, it's crucial to know how much you need. Our Pool Salt Calculator is the perfect tool to determine the exact amount based on your pool's volume and current salt levels.
What Makes a "Good" Pool Salt? The Three Pillars
When you're at the store looking at bags of salt, there are three key characteristics that define a high-quality pool salt suitable for your SWCG system.
1. High Purity (99.8% NaCl or Higher)
This is the single most important factor. Pool salt should be as close to pure sodium chloride (NaCl) as possible. The reason is simple: impurities cause problems. Lower-grade salts can contain contaminants like dirt, minerals (iron, copper, manganese), and phosphates.
- Metals: Iron and copper can cause ugly brown or green stains on your pool's plaster, pebble, or vinyl liner surfaces. These stains can be difficult and expensive to remove.
- Phosphates: These are a primary food source for algae. Adding phosphates to your pool via low-quality salt is like giving algae a feast, which will increase your chlorine demand and make algae blooms more likely.
- Dirt and Debris: Can lead to cloudy water and require extra filtration and cleanup.
Always look for packaging that explicitly states the salt is "pool salt" and check for a purity level of at least 99.8%.
2. Quick-Dissolving Granules
Pool salt is specifically milled to be a fine granule that dissolves relatively quickly in water. This is important because salt that sits undissolved on the bottom of a pool for too long can be highly corrosive to the surface. It can cause pitting in plaster and concrete pools and can bleach or damage vinyl liners.
When you add pool-grade salt, you should run your pump to circulate the water and brush the pool floor vigorously to help the granules dissolve and prevent them from piling up in one spot.
3. Non-Iodized
Pool salt should never be iodized. While the iodine in table salt isn't harmful in small quantities, it's an unnecessary additive that could potentially cause some discoloration on equipment or fittings over time. All reputable pool salt brands are non-iodized.
Types of Salt to AVOID in Your Pool
Using the wrong salt is one of the most common—and avoidable—mistakes a saltwater pool owner can make. Here's what to steer clear of:
1. Water Softener Salt
This is a big one. While it's also sodium chloride, water softener salt is typically sold in large pellets, crystals, or blocks designed to dissolve very slowly over time in a water softener tank. This slow-dissolving nature is terrible for a pool. The pellets will sit on the pool floor for days, creating highly concentrated saline spots that can easily damage your liner or plaster. Furthermore, many water softener salts contain anti-caking agents or other additives that you don't want in your pool.
2. Table Salt
While chemically similar, table salt is not a practical or cost-effective option. It's often iodized and contains anti-caking agents like Yellow Prussiate of Soda (YPS), which can cause yellow stains on pool surfaces. Additionally, you would need an enormous quantity of small, expensive containers to salt an entire pool, making it prohibitively expensive compared to buying 40lb bags of pool salt.
3. Rock Salt (Ice Melt Salt)
Absolutely not. Rock salt is intended for melting ice on roads and is extremely impure. It is filled with dirt, sand, and other minerals that will turn your pool water into a cloudy, stained mess. The impurities in rock salt will introduce metals, phosphates, and other contaminants that will wreak havoc on your water chemistry and potentially damage your equipment.
Conclusion: Stick to the "Pool Salt" Label
The solution is simple: always buy salt that is specifically packaged and marketed as "Pool Salt." Brands like Morton, Diamond Crystal, and many others produce high-quality salt that meets the three critical criteria: high purity, quick-dissolving granules, and being non-iodized.
While it might be tempting to save a few dollars by using a different type of salt, the potential cost of repairing a stained liner or a damaged salt cell far outweighs any small initial savings. Protecting your investment starts with using the right ingredients. Once you know how much salt you need with our calculator, head to your local pool store and purchase bags that are clearly labeled for swimming pool use. Your pool and your equipment will thank you.