Ahhh rust stains, those pesky little brown stains (or spots) that seem to appear out of nowhere and just ruin your pool's crystal blue color, really big eyesore. Although we've already talked about how to identify and treat different types of pool stains, today due to popular demand we're going to focus on rust stains!
Sources of pool rust stains
Before we start removing rust stains, let's first go through the different sources of rust stains so we can prevent the stains from coming back in the future after we've taken care of the stain.
- Rust from metal objects - Things like bottle caps, bobby pins, metal buttons and the like that somehow find their way into your pool will start rusting about a day after falling in, especially if left undisturbed. These are basically superficial spots that are gone forever after treatment.
- Recurring Rust Stains - At first many people will think this is just rust from metal objects that have fallen into the pool which has been vacuumed but once the stain has been treated lo and behold, after a few days the stain will be back in the exact same spot ! These types of stains are usually caused by small cracks in your pool surface and water seeping into the reinforcement underneath. This type of discoloration is also known as “concrete cancer” because it recurs and gets worse at an increasing rate over time. If you spot these types of stains, it is advisable to contact a pool professional who will make some repairs to your pool to seal the cracks.
- Metals in pool water oxidize - even if you clean your pool carefully, metals from the source water can get into your pool, especially if your area uses well water or if the pipes that bring your pool water are made of iron.
- "Rust Plating" - This occurs with improper use of copper-based algaecides. Usually this happens when high levels of chlorine (from shocks or from the return jets if you have a saltwater chlorinator) react with the copper from copper-based algaecides. More on that later, but as a prevention tip, simply avoid high levels of chlorine when using copper-based algaecides.
Techniques for removing rust stains in the pool
Here are some of the techniques we use here at Mr Pool Man to remove rust stains from our pool.
Use of vitamin C tablets
With the pandemic, every household should have some vitamin C on hand and if you've overdone stocking up on vitamin C then this is the perfect use for you! Using vitamin C tablets is perfect for stain removal from metal objects. For tiny rust spots, just take a vitamin C pill and rub it on the spot and you should see instant results like magic! How does this work? Well, vitamin C pills are basically ascorbic acid, which is pretty acidic, and the acid will melt the rust away! Simple and easy solution to removing small stains.
Note: Make sure you have the traditional vitamin C pills and not the newfangled non-acidic sodium ascorbate vitamin C pills that are gaining popularity as they do nothing for stains. Remember, the acid does the work!
The "Sock Method"
If you've been around pools for a while, you've probably heard of this rust stain removal method. This is perfect for large patches of rust stains or those on the bottom of your pool where hand rubbing those stains just isn't possible. You will need a handful of vitamin C tablets (regular vitamin C again) and an old sock (SERIOUSLY MAKE SURE THE SOCK IS CLEAN). So if the washing machine goblins have stolen one of your socks, don't throw away the unsurpassed sock, save it for future use.
Take a handful of vitamin C and pour it into the broth and tie it up. Give it a few good hits to crack and crush the pills inside, making them much easier to get into the water. Use the sock like a sponge to remove rust stains on steps and on your plumbing. For deeper stains, you can tie the sock to the end of your telepole and use that in place of your brush head. Hold the sock against the stain for a few seconds to allow the acid to eat through the stain and then continue brushing it with your pool brush, this should remove the stain easily.
No vitamin C tablets? No problem!
Do you have rust stains you want to remove but vitamin C is expensive? Then no problem, you can use some Zodiac pH Down tablets instead of vitamin C tablets. Zodiac pH Down Charts are made with Sodium Bisulfate, which is basically an acid and works just as well on rust stains as Vitamin C! Just be careful and use proper protection like gloves and don't touch your eyes without washing your hands as sodium bisulfate is much more corrosive than vitamin C.
Wash your pool with acid
If your pool has rust stains all over it and stain removal doesn't seem like a wise use of your time, acid washing is one of the quickest ways to bring out your pool's natural color and remove common rust stains. We have no way of acid washing your pool ourselves as this will require draining your pool and this is best left to pool professionals.
What we have for you is a way to do a no-drain acid wash that you can do yourself! It's about lowering the pH of your pool to an acidic state, letting it eat through the stains, and brushing it thoroughly. We've outlined the entire process in our swimming pool hack:Instructions on how to wash with acid without a drain here!
Use Zodiac's all-in-one stain remover
While DIY methods work well, it's always good to know that there are ready-made solutions that are tailor-made to treat rust stains, and one of those solutions is Zodiac's all-in-one stain remover. This stain remover is made up of 50/50 oxalic acid and citric acid making it perfect for pool use. To use Zodiac's all-in-one stain remover, turn off your filtration system to allow the stain remover to settle near the stains. Sprinkle the stain remover generously on the areas to be treated and leave it on overnight. Brush the stains in the morning and that should solve your stain problem! After brushing, run your filtration system normally to catch any dirt you loosened while brushing.
Rust stains in your pool aren't just eyesore, they can be a symptom of something else! Deal with rust stains as soon as you spot them and see if they come back to find out what exactly is causing them to prevent them from ever coming back!
Do you have any questions on this topic or the products presented? Don't worry, we're here to help! Drop us a question below and we'll get back to you as soon as possible.
Have fun swimming :)