How to Avoid Common Pool Maintenance Mistakes

Whether you’re a new pool owner or have owned one for years, proper pool maintenance ensures your inground pool remains a sparkling oasis, extends its lifespan, and minimizes costly repairs. If you’re a fiberglass pool owner, you probably have heard that fiberglass pools are the lower maintenance option among pool types. However, lower maintenance does not mean no maintenance. The following tips can help you avoid the common mistakes people make when caring for their inground pool.

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Tip 1: Mind your Water Balance 

Failure to regularly monitor your pool’s water balance is probably the most common (and costly) mistake. Clear water does not inherently mean balanced water. Water can appear crystal clear while individual factors are in range but still out of balance. Unbalanced water can cause permanent damage to the inground pool shell. 

Test your water frequently. You’ll get the best accuracy with a high-quality test kit instead of test strips. Alternatively, you can take your water sample to a pool supply store for testing. It’s important to note that temperature affects water balance, so don’t leave your water sample in a hot car while you run errands. Take the sample directly to the store after collecting the water.  

We recommend using the Langelier Saturation Index (LSI) to balance your pool’s water chemistry. You can more easily do this via The Orenda Calculator™ on your smartphone or computer. See also our “water balance cheat sheet” for guidance on properly maintaining your fiberglass pool’s water chemistry. For Thursday Pools’ fiberglass pools, pair these resources with our owner’s manual, which provides information, including our recommended water chemistry levels for comparison, what pool maintenance chemicals to avoid, and more.


Tip 2: Backwash Regularly

Many pool owners start the season off by backwashing their filters once per week. As the season progresses, they often aren’t as dedicated to it. Your filter plays an essential role in the continued enjoyment of your pool, and proper backwashing can reduce your pool maintenance costs in the long run. Some reasons you should backwash regularly include the following.

  • Efficiency: A clean filter is more effective at trapping debris. A clogged filter can’t perform efficiently, putting more strain on your pool pump and reducing its lifespan.
  • Water Quality: Regular backwashing helps maintain clear and sanitary pool water. A dirty filter can harbor bacteria and allow more contaminants to circulate into the pool.
  • Prevent Damage: Over time, excessive pressure from a dirty filter can cause damage to the pool’s filtration system. Regular backwashing helps prevent such issues.

It’s important to follow the specific guidelines provided by your filter’s manufacturer, as different types of filters (such as sand, DE, or cartridge) might have different needs and procedures for backwashing.

Backwashing too frequently can damage the filter, so use your pressure gauge reading to know when to backwash. Typically, you should backwash when the pressure gauge on the filter reaches 8-10 PSI (pounds per square inch) over the normal operating pressure. The standard operating pressure varies by filter, so knowing your baseline pressure when the filter is clean is essential.


Tip 3: Keep Up Your Water Level 

Maintaining the water level at the midpoint of the skimmer opening allows your pool’s systems to operate correctly. The skimmer is designed to pull debris from the pool’s surface before it sinks to the bottom of the pool, becoming harder to remove. If the water level is too high, the skimmer door may not work correctly, reducing its efficiency at collecting surface debris. If the water is too low, the skimmer may suck in air, which can lead to airlocks or damage the pool pump by causing it to run dry.

The proper water level also provides balanced circulation. The pool pump must pull water through the skimmer for filtration and chemical treatment. Maintaining the correct level helps ensure that the water circulates properly, distributes chemicals evenly, and keeps the temperature consistent throughout.

While you’d have to go lower than the skimmer, in fiberglass pools, a water level that drops too low can cause the fiberglass wall panels to warp or bulge from ground pressure. In extreme cases, if a fiberglass pool is emptied or the water level is significantly reduced, there is a risk that the pool can begin to “float” or shift out of position. This is due to groundwater pressure pushing against the relatively lightweight fiberglass structure, which can lead to major structural damage. 


Tip 4: Pay Attention to What You Put in Your Pool

Maintaining an inground pool involves using specific chemicals and tools that are compatible with its construction to ensure longevity and preserve the quality of the pool surface. Here’s a breakdown of what’s generally recommended and what should be avoided for fiberglass pools:

Good Chemicals for Fiberglass Pools

  1. pH Balancers: Keeping the pH level between 7.2 and 7.6 is crucial. To maintain this balance, use pH increasers (soda ash) or decreasers (muriatic acid or sodium bisulfate) are acceptable.
  1. Alkalinity Increasers: Baking soda (sodium bicarbonate) is commonly used to maintain total alkalinity, which should be kept between 80 and 120 ppm (parts per million) to stabilize pH levels.
  1. Calcium Hardness Increasers: Fiberglass pools require less calcium than concrete pools. The ideal range is around 150 to 200 ppm. Use calcium chloride sparingly to adjust levels when needed
  1. Chlorine: Keep total chlorine at 1 to 3 ppm. When your water is balanced to LSI, you will need less chlorine. High chlorine levels can damage the gelcoat finish over time.
  1. Non-Copper Algaecides: Avoid algaecides that contain copper, as they can stain the fiberglass. Look for polyquat algaecides, which are safe for fiberglass.

Harmful Chemicals for Fiberglass Pools

  1. Completely avoid Calcium Hypochlorite (Cal Hypo), as it can cause scaling and damage to the gelcoat.
  1. Avoid “shocking” the pool with high doses of chlorine, especially if not diluted properly, as it can lead to discoloration and damage to the fiberglass surface. 
  1. Copper-based algaecides can stain fiberglass surfaces, leading to blue-green stains that are difficult to remove.

Good Tools for Fiberglass Pools

  1. Soft-Bristle Brushes: Use soft nylon brushes to clean the pool’s sides and bottom. Fiberglass surfaces are relatively delicate, and using soft brushes will prevent scratches.
  1. Manual or Automatic Cleaners: Ensure that any automatic pool cleaner is suitable for fiberglass pools, typically those that do not require connection to the pool’s filtration system and operate gently.

Tools to Avoid in Fiberglass Pools

  1. Never use wire brushes or abrasive tools, as they can scratch and damage the gelcoat finish.
  1. Some heavy-duty vacuums designed for concrete pools can be too abrasive for fiberglass surfaces.

When maintaining a fiberglass pool, following the manufacturer’s specific recommendations for chemicals and cleaning tools is crucial.


Final Thoughts

Keep a regular pool maintenance schedule. As with many things in life, consistency is vital. Developing a regular, thorough, and routine maintenance schedule helps keep your pool in tip-top shape. Above all, the most significant maintenance mistake is not doing maintenance.