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How to Prevent and Remove White Water Mould
If you’ve noticed an unpleasant cloudiness or white slime-like substance in your once-sparkling swimming pool water, you might have a problem with white water mould.
Luckily with the right maintenance and swimming pool chemicals, clearing up this issue and preventing it from recurring is relatively easy.
White water mould is a naturally-occurring fungus that may form in your pool. The mould takes on the appearance of mucus or torn-up tissue – safe to say it’s not something you want to be swimming around in!
This mould is an organic contaminant, so if it starts cropping up, it's likely your pool is not being properly maintained. It can form when there is poor water circulation and imbalanced chemicals.
White water mould can be quite resistant to certain chemicals as it depletes the oxidiser levels in your water, making your pool chlorine less effective as it becomes harder to maintain the right sanitiser levels.
It’s also worth noting that UV rays are highly effective at killing white water mould, so indoor pools that don’t get as much exposure to sunlight are more prone to developing mould problems than outdoor pools – although outdoor pools may still experience it if they’re particularly dirty.
Unlike other contaminants, white mould itself is not harmful to humans. However, it is unsightly and can clog your equipment, along with being a fairly good indicator that your pool isn’t clean, so might not be safe to swim in. Once you notice signs that it is present, it’s best to tackle the problem ASAP.
When you tackle the removal of this mould, you must be thorough. If small traces are left, they can multiply and cause issues again, even after you’ve done a deep clean.
It’s no good clearing your water if your filter is contaminated, as this will only re-circulate the mould back into your pool. So, first, you must make sure your filter is completely clean.
For sand filters, this will mean backwashing the filter, and for cartridges, rinsing them before using a filter cleaner should do the trick.
Next, you’ll want to set your cleaning chemicals up for success by ensuring the water’s chemistry is just right. Test the water and rebalance it according to the recommended levels. You can find out more about doing this in our guide on how to balance pool water.
You will now need to treat your water with a very strong dose of chlorine shock. A regular dose will likely not be enough to kill off the mould, so you may need to triple or quadruple your usage shock amount (4 pounds of calcium hypochlorite per 10,000 gallons of water).
Make sure your filtration system runs continuously after you've administered the shock to ensure it is circulation throughout your pool.
Once the chemicals are set to work, it's time for you to do some cleaning. Brush the pool’s floor and walls to dislodge any white mould from the surfaces. After giving everything a brush down, run your pump overnight, to allow your filter to trap a good amount of the contamination you’ve brushed away.
Then, brush the pool’s surface again to target any lingering spots. Use a pool vacuum to remove these last little bits.
Also take this chance to thoroughly clean your pool equipment, including ladders, fittings, lights and pool toys or anything else that may have come into contact with the mould to ensure you don’t accidentally leave any spots to grow.
Your filter will have now picked up the lingering white mould, so it's a good idea to do a secondary clean and make sure it’s fresh for your newly clean water.
Finally, test your water and rebalance it if necessary, bringing the pH, alkalinity and chlorine levels back to where they should be. For the next few days, keep an eye out for any recurring mould – you may want to brush and vacuum for the first few days post-mould removal to make doubly sure it doesn’t come creeping back.
To make sure you don’t have to treat it again, you’ll want to remain vigilant about preventing the future growth of white water mould in your pool. There are a couple of simple things you can do to avoid recontamination.
Keep on top of a regular pool cleaning schedule to stop any mould issues in their tracks. This means being careful about maintaining the water’s chemistry and using pool cleaning supplies like brushes, sponges and pool vacuums to keep the surfaces clean.
UV rays help kill white water mould, so when possible, expose your pool and accessories to sunlight.
Regularly clean your filter with chemicals to prevent the fungus from establishing itself within your swimming pool systems and spreading throughout the entire pool.
Along with white water mould, other moulds, bacteria and algae can form in your pool if you’re not careful about cleaning it properly. So, to enjoy your swimming pool to the fullest, it really is essential that you use the right chemicals in line with a regular routine!
