page loader
salt - magnified
Image of swimming pool salt under a microscope.

Swimming pool salt causes stains

Almost daily we receive calls from distressed clients saying the following – “I got some cheap swimming pool salt from my local hardware store and now I’ve got these ugly brown stains in my pool”.  Often, this brown staining becomes evident within hours of adding the salt to the water.  Many pool owners around the world face this issue. What are the key differences between bad salt and good salt and why does it matter to your pool? Let’s find out.

Good pool salt versus bad.  What’s the difference?

All pool salt has the same basic properties. However, the mineral, water, contaminate and metal content found in pool salt can vary significantly from brand to brand.  For this reason, the salt used in your pool has a significant impact on the total volume of minerals and metals that are dissolved into your pool water over time. These minerals will later discolour and stain your pool interior, particularly if your pool water balance is not maintained.

What makes this an issue is that pool water evaporates over time but minerals and metals do not.  These minerals remain suspended in the pool water, even when the pool is topped up with fresh water. Remember, quality salt will significantly slow down this mineral accumulation in your pool.

How can I recognize poor quality salt?

There are 5 things that typically characterize poor quality salt.  They are as follows –

  1. Crystal size is large
  2. Salt is discoloured
  3. It is slow to dissolve
  4. It turns the water murky 
  5. Salt leaves brown stains in your pool

If the salt brand you are currently using matches ANY of the attributes in the list above then we strongly suggest trying an alternative.

What does good quality salt look like?

There are five things that characterize good quality pool salt.  They are as follows –

  1. Crystals are very small
  2. Crystals are fast dissolving in water
  3. Salt bag shows a purity level of more than 99.5%
  4. Product is brilliant white in appearance
  5. Pool water feels soft and comfortable for swimmers

Did you know that the average pool owner only spends around $120 per year on swimming pool salt?  It is unwise to cut corners by using cheap salt when the consequences can be so costly.

Good quality salt will cost a fortune right?

Most pools need around 10-12 bags of salt per year to maintain correct salt levels.  The cost difference between poor and high quality salt is around $4 per 20kg bag.  So the $50 additional cost for quality salt is hardly a budget blowout for pool owners.  On the other hand, the cost of removing stains caused from poor quality salt can sometimes be over $1,200.00. From a financial perspective, cheap salt does not make any sense at all.

There are times when inexpensive brands sell reasonably high quality batches of salt.  However, less expensive brands need to source lower grade salt in order to meet the low prices some consumers demand.  Therefore, the chances of purchasing a contaminated batch of salt is generally higher with less expensive brands. Remember, high purity, fine salt is in demand in several industries and so it simply costs more to buy.

Swimming pool salt – qualities

Another thing to be aware of in terms of cost is that salt is sold by weight not by volume.  This means that some low cost brands will bulk buy moisture rich low quality salt at a low price in order to undercut their competitors.  Also, because moisture is not desirable in pool salt, it is sells for a lower price.  Because moisture is heavy and salt is sold by weight, it means that if the salt moisture levels are high then you’re actually paying for water rather than salt! Therefore, the actual amount of pure salt you have in your salt bag will depend on the quality of the salt, not the total weight of the bag.

Although no brand or batch of salt is 100% pure and completely free of all contaminates, high quality brands generally have better quality control and accurate measures to monitor mineral content during bagging.  Remember, when quality salt is added correctly it saves you money over the life of your pool and will actually cost you less in the long term.

How do I remove salt stains from my pool?

Stain stains are removed with our granular stain compound without draining the pool or acid washing. So please feel free to call The Pool Stain Removers today.

Do you have any comments or experiences with salt that you would like to share?  We look forward to hearing about them via the email address on our website.

salt stains in swimming pool
Our client in Melbourne, Australia placed a full bag of salt on the steps of their pool and left it to dissolve overnight. The next morning the steps and the entire pool had a horrible brown stain caused from contaminates within the salt.


Colour, crystal size and purity –

Customers upset and complaining about staining from cheap pool salt –

Adding salt to your pool correctly –

Salt quantity needed per year –

Long term benefits of using good quality salt –

Salt graded by water content –