Iron Stains in Pool - How To Remove Them?
Pool water typically contains many dissolved trace minerals, including metal particles such as copper and iron. Iron can build up slowly on surfaces in your pool over time, but some chemical treatments increase the likelihood of iron particles building up in your pool, leading to unsightly stains.
How to Identify Iron Staining
Before making any attempts to remove stains from your pool, it’s important to make sure you have correctly identified the type of stain that is present to avoid ineffective treatment. Stains can often be identified by their colour.
Staining from iron typically presents on your pool as a rust colour, ranging from burnt yellow and orange tones to darker browns. Other trace metals can present as different colours: copper will produce light-green stains, manganese produces dark-purple stains, and silver typically produces black stains.
If the stains in your pool are shades of brown with yellow and green tints, you might have organic staining, which requires a different removal method.
While it can be helpful to determine whether you have organic staining or metal staining, it’s not necessary to know exactly what type of metal is staining your pool. Different types of metal staining can occur at the same time, and can often be removed simultaneously by the same product.
You can spot test a pool stain by scrubbing it thoroughly with a bristle brush and shock chlorine powder. Most organic stains yield easily to scrubbing, especially when an abrasive cleaning agent is used, but a stain caused by iron or another type of metal will show almost no change.
What Causes Iron Staining
Iron staining is caused when trace minerals present in pool water build up on the surfaces of your pool. This can happen slowly over time, especially if your pool is fed with bore water, but more rapid staining can also be caused by other chemical pool treatments.
The most common cause of sudden-onset iron staining is chlorine shock treatments. When chlorine is added to a pool in large concentrations, it can cause trace metals like iron to form deposits on the side of your pool at a faster rate. Pool chlorine causes heavy metals to oxidise, which leads to the build-up of trace minerals and forms stains.
If staining is a common occurrence in your pool, there are steps you can take to prevent it. For example, if your pool is fed with particularly hard water, you may use a product like Calcium Down Hardness Reducer to clear up water quality and reduce calcium related scaling. As an added bonus, this product is also effective at preventing iron stains.
If you don’t have a calcium scale problem in your pool, and your stain issues tend to be with trace metals, we recommend Serious Stain Inhibitor.
This works to prevent all types of trace mineral build-up including calcium and lime scaling, and is also especially effective at preventing metal stains. This product can also be used to remove fresh stains, making it a great option for quick-action the first time you notice stains forming in your pool.
How to Remove Iron Staining From Your Pool
The easiest way to remove iron stains in your pool is through the use of stain remover products. These can be added to your pool water and do most of the work for you, with no scrubbing required in most cases.
Our favourite product for removing stains is Lo-Chlor Multi-Stain Remover. This product is one of the best, in our opinion, because it can be used to remove both metal and organic stains, works great all-over your pool or as a spot treatment, and also aids in the prevention of future stains.
If you are confident that the stains in your pool are iron, you may prefer to attack it with a stain remover intended specifically for iron buildup. This product is the best option for persistent iron stains, including stains that have been left untreated for a while.
When using a stain remover, always be sure to follow the instructions provided on the product label. Many products require that you lower chlorine levels (using a chlorine neutralizer) and adjust the pH of your water before introducing them to your pool.
Your stain removal product will also have special instructions for bringing your pool back into proper chemical balance after treatment, which is a crucial step to ensure that your pool is safe for use.
If you don't get much success with the Lo-Chlor product, consider using an ascorbic acid stain remover, which often helps with iron staining.
Iron stains are an unsightly nuisance that can sometimes be hard to distinguish from other types of stain. Luckily, once identified, most iron stains on your pool’s surfaces can be easily removed through the use of stain remover products. Learning more about stains is an important step in stain removal, but we also recommend taking active measures to prevent any future stains.
Do you have any questions about removing iron stains from your pool? Leave us a comment down below, we’d love to hear from you!
A chemical engineer by trade, Louis is committed to debunking myths in the pool industry by explaining the underlying chemistry and making it accessible to all.