Rust Spots & Stains In Your Pool - How To Remove Them?
Rust spots and stains in your pool tend to show up as unsightly colored patches that typically occur along the bottom of your pool’s lining. There are many causes of rust spots, with some of these causes being more serious than others.
Luckily, rust stains are not difficult to remove. Most stains that form on smooth pool surfaces can be removed by scrubbing them with a special acid. Rust spots on pebblecrete pools can be more challenging to remove due to the rough surface of the pool, but removal is not impossible.
In this article, we will cover how to identify rust stains, the causes of rust spots in your pool, how to remove rust stains, and ways that you can prevent them from appearing again in the future.
How to Identify Rust Stains
Rust stains tend to appear along the lining and bottom of your pool as small patches of a reddish-brown colour that can also contain orange tones.
Rust stains in pebblecrete pools can sometimes be more difficult to notice until they have become severe due to their ability to blend in with the natural finish.
It’s important to make sure that your rust stains are indeed caused by metal and not actually left by organic debris. In order to determine this, you will want to perform a scrub test. To do this, scrub the stain that you are concerned about with some crushed chlorine tablets.
If the stain shows lots of improvement after some moderate scrubbing, it is not rust, but a stain caused by organic debris. If the stain shows little to no change after scrubbing, you have a rust stain that is typically caused by iron.
Causes of Rust Spots
Rust spots and stains in your pool are typically caused by metals that should ideally not be in contact with your pool’s water or lining.
The most common sources of rust stains are metal items that are dropped by swimmers or during pool and backyard maintenance. These include items such as hair pins, certain types of jewellery, buttons, eyelets, screws, and nails.
You may also develop rust stains as a result of filling your pool with bore water. Bore water can be higher in dissolved metals and minerals than municipal water sources, and if your water has a naturally high concentration of iron, then rust stains become more likely.
Sometimes rust spots develop near pool drains, ladders, and skimmer baskets, and this typically indicates that components of these parts are rusting. If you notice stains in these areas, make sure to investigate your pool’s structures for damage and replace any components that are showing signs of oxidation and decay.
Rust spots themselves can also be a sign of more serious structural damage. Sometimes, iron rebar used in the structuring of concrete pools can leech through the pool’s surface and form rust stains, especially if there are cracks or other damage to the lining.
These rust stains will come back in the same spot once treated, and are a sign that you may need to have your pool’s structural integrity checked by a professional.
How to Remove Rust Stains in Your Pool
Unlike other types of metal staining, there is a viable at-home option for rust stain removal that you can complete without the purchase of additional pool chemicals. All this method requires is a clean sock that you don’t mind getting roughed up a bit, and some ascorbic acid containing vitamin C tablets.
To remove rust stains from your pool using the sock method, you will first want to fill the sock up with a small amount of vitamin C tablets. The amount in the sock should roughly resemble the size of a tennis ball. Once you have put the tablets in the sock, tie the sock off above the tablets.
Before getting ready to scrub your stains, crush the tablets in the sock up a bit more. To do this, you could hit the sock against a hard surface or try stepping on it. Once the vitamin C is partially crushed, use this part of the sock to scrub your rust stains.
The vitamin C functions as ascorbic acid, an effective component at weakening rust stains that makes them easier to scrub away. Although this method is effective, it does require a fair amount of manual labour, and can be difficult to complete on rough linings such as those found in pebblecrete pools.
If you are looking for a less labour-intensive option for removing rust stains from your pool that is capable of reaching all the nooks and crannies with ease, we recommend using a stain removal product. These products are typically added to your pool when the pump is shut off, and once left to stand for 2-3 days will dissolve your stains using powerful acids without any scrubbing.
Stain removers that comes in granulated form work great on rust stains as well as any other types of metal or organic staining that you may have in your pool. They are strong, and their effects can be further intensified by dropping the pH of your water before using it.
If you are unable to remove your stains via these methods, or if you have widespread rust stains caused by a pool that has been neglected or abandoned for a period of time, you might want to consider getting your pool acid washed. Acid washing often requires the help of a professional, but can be an effective way to remove more severe rust stains that have been left unattended.
Preventing Rust Spots in the Future
In order to prevent rust spots from forming in your pool, try to avoid leaving metal objects on the bottom of your pool for long amounts of time. Although hair pins and similar items may fall off of swimmers, rust from them can be prevented if these items are removed promptly.
If your rust stains are caused by dilapidated pool equipment or rebar (aka concrete cancer) seeping through a fractured pool lining, you will need to get these structural issues fixed in order to prevent further staining.
Rust stains that are caused by high amounts of iron in bore water can be prevented using special products that keep small particles of metal from depositing and oxidising on the surfaces of your pool. We like this stain inhibitor because one dose can prevent stains in your pool for six months or more. It is also safe for swimmers and has no off-putting smell.
Although rust stains are undesirable, they are not always a cause for concern. Many rust stains are caused during typical pool use by using toys not intended for use in water, lost hair pins or eyelets, or loose screws or nails that have fallen in.
Some rust stains, particularly those caused by issues with your pool’s rebar, are an indicator of a more serious problem. Rust stains caused by exposed rebar are a sign of heavy structural damage that will only get worse with time and can affect the integrity of your pool if not fixed by a professional.
Do you have any questions about rust stains and spots in your pool or how to remove them? Let us know in the comment section!
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.