As winter bids adieu and warmer temperatures beckon, many pool owners eagerly anticipate the joy of diving back into their inground oasis. However, recent years have seen a curious trend emerge – warmer winters, increased prevalence of white water mold, and the need to open pools earlier than usual. In this blog post, we’ll delve into these interconnected phenomena and explore the benefits of borates in combating white water mold while ensuring a pristine pool environment.

Warm Winters and Early Pool Openings

In response to the challenges posed by warmer winters and the increasing prevalence of mold issues, many pool owners are finding it necessary to open their pools earlier than usual. This proactive approach allows them to address potential problems and tackle mold issues before the official swimming season kicks off. By opening their pools ahead of time, owners gain a head start in performing necessary maintenance tasks, ensuring that their pool is in optimal condition for enjoyment when warmer weather arrives.

The Rise of White Water Mold

White water mold, scientifically known as Pseudomonas or Saprolegnia, presents itself as a persistent nuisance in swimming pools or spas, often with distinct visual cues and functional disruptions. This type of mold typically manifests as cloudy patches or streaks in the pool water, resembling cotton-like masses, used toilet paper, or filmy layers on pool surfaces and filter media. Its appearance can range from white to grayish in color, creating an unsightly and uninviting atmosphere for swimmers.

Beyond its aesthetic implications, white water mold can also wreak havoc on pool equipment, particularly filtration systems. As the mold proliferates, it can clog pool filters and impede water circulation, leading to reduced filtration efficiency and compromised water quality. This obstruction not only diminishes the effectiveness of the filtration system but also necessitates frequent maintenance and cleaning efforts to restore optimal functionality.

In essence, white water mold poses a dual threat to pool owners, tarnishing the visual appeal of their pool environment while imposing logistical challenges in maintaining clean and healthy water conditions. Its tenacity underscores the importance of proactive measures, such as early pool openings and strategic chemical treatments, to mitigate its impact and preserve the integrity of the swimming experience.

White water mold on a spa cartridge filter

Removing White Water Mold from Pool Filters: Strategies for All Types

White water mold poses a formidable challenge for pool owners, regardless of the type of filtration system installed. Whether you have a sand, cartridge, or DE (Diatomaceous Earth) filter, effectively addressing mold-related issues requires a systematic approach tailored to the specific characteristics of each filter type. Here’s how to remove white water mold from different types of pool filters:

1. Sand Filters:

Sand filters, with their simple design and ease of maintenance, are commonly used in residential swimming pools. To remove white water mold from a sand filter:

  • Backwash the Filter: Start by initiating a backwash cycle to flush out any accumulated debris and mold from the filter media.
  • Clean the Filter Tank: It is best to just completely replace your sand if you have white water mold. After backwashing, remove the filter tank’s lid and visually inspect the sand bed for signs of mold growth. If mold is present, dispose of your sand.
  • Rinse and Recharge: Thoroughly rinse the filter tank with water to remove any loosened mold and debris. Once clean, add a specialized sand filter cleaner or pool filter aid to the filter tank to help inhibit mold growth and improve filtration efficiency, and replace the sand or consider glass media or a DE Filter.

2. Cartridge Filters:

Cartridge filters offer decent filtration performance and are relatively easy to maintain. To remove white water mold from a cartridge filter:

  • Remove the Cartridge: Turn off the pool pump and remove the cartridge filter from its housing. Inspect the cartridge for signs of mold growth, paying particular attention to the pleats and crevices.
  • Clean the Cartridge: Keep in mind it will probably be best to just replace cartridge media completely if you end up with white water mold, especially if you see a lot of mold jammed up in the pleats as in the photo above. If you want to try to salvage it, rinse the cartridge thoroughly with a high-pressure hose to dislodge any mold and debris.
  • Disinfect: After cleaning, soak the cartridge in a garbage can filled with a chlorine bleach solution (one part bleach to five parts water) for several hours to disinfect and kill any remaining mold spores. Rinse the cartridge thoroughly with water before reinstalling it in the filter housing.

3. DE (Diatomaceous Earth) Filters:

DE filters provide superior filtration capabilities and will do the best job of removing white water mold. The mold will, however, quickly clog up the filter and require treatment and disassembly to completely get rid of it. To remove white water mold from a DE filter:

  • Backwash and Disassemble: Begin by backwashing the DE filter to remove any loose debris and mold from the filter grids. Once backwashing is complete, turn off the pump and carefully disassemble the filter to access the grids.
  • Clean the Grids: Rinse the filter grids or fingers with a hose to remove any mold, debris and old DE. You may notice the mold coming off the grid like used toilet paper. Using a pressure washer can assist but you must be very careful not to tear the grid when using high pressure. 
  • Disinfect: After cleaning, soak the filter grids in a garbage can filled with a chlorine bleach solution (one part bleach to five parts water) for several hours to disinfect and kill any remaining mold spores. Rinse the grids thoroughly with water before reassembling the filter.

Regardless of the filter type, regular maintenance and preventative measures, such as maintaining proper water chemistry and filtration, are essential to minimize the risk of future mold growth and ensure clean, healthy pool water for all to enjoy.

The Role of Borates in Pool Maintenance

Enter borates – a powerhouse compound in pool maintenance often overlooked by many pool owners. Borates, typically in the form of boric acid or borax, serve multiple functions in pool water:

  1. Algae Prevention: Borates act as an effective algae inhibitor, disrupting the cellular processes of algae and preventing their growth. By maintaining a proper borate level in your pool, you can significantly reduce the risk of algae blooms, even in warmer temperatures.
  2. pH Buffering: Borates help stabilize the pH levels of pool water, preventing fluctuations that can lead to corrosiveness or scaling issues. This buffering effect ensures that your pool water remains in the optimal pH range for comfort and safety.
  3. White Water Mold Control: One of the lesser-known benefits of borates is their ability to combat white water mold. By inhibiting the growth of fungi and bacteria, borates create an environment hostile to the development of white water mold, thus keeping your pool water crystal clear and inviting.

The Benefits of Borates Beyond Mold Control

Apart from their prowess in mold prevention, borates offer a host of additional benefits for pool owners:

  • Water Softening: Borates impart a soft, silky feel to pool water, enhancing the swimming experience and reducing skin and eye irritation.
  • Extended Chlorine Efficiency: Borates help stabilize chlorine levels in pool water, allowing for more efficient disinfection and reducing the need for frequent shock treatments.
  • Cost-Efficiency: While initially an investment, incorporating borates into your pool maintenance routine can lead to long-term cost savings by reducing the need for other chemical treatments and prolonging the lifespan of pool equipment.


As the seasons shift and pool season beckons, proactive pool maintenance becomes paramount, especially in the face of warmer winters and the increased prevalence of white water mold. Embracing the power of borates offers a holistic solution, not only in combating mold but also in ensuring a pristine, enjoyable swimming environment for you and your loved ones. So, as you prepare to unveil your pool for another season of aquatic bliss, consider harnessing the potential of borates to keep your oasis sparkling and inviting all year round.