What is TDS (Total Dissolved Solids), and Why is It Important?

TDS refers to the amount of dissolved substances in your water, including minerals, chemicals, and organic material. High TDS can cause cloudy water, scaling, or chemical inefficiency. If TDS is too high, it's time to drain and refill the tub.

What is TDS?

TDS stands for Total Dissolved Solids, which refers to the combined total of all organic and inorganic substances dissolved in water. These substances include:

• Minerals (calcium, magnesium, sodium, etc.)

• Salts (chlorides, sulfates, and carbonates)

• Metals (iron, copper, lead)

• Chemical additives (chlorine, bromine, algaecides, and stabilizers)

• Organic matter (body oils, sweat, sunscreen, and debris)

Over time, as water evaporates, these dissolved solids accumulate, affecting water clarity, chemical balance, and overall water quality.

Why is TDS Important?

A high TDS level can cause various water problems, including:

• Cloudy or dull water: High TDS levels make it difficult to maintain crystal-clear water.

• Chemical inefficiency: Chlorine and other sanitizers become less effective, allowing bacteria and algae to grow.

• Scaling and corrosion: Excess minerals lead to scale buildup on pool surfaces and equipment.

• Eye and skin irritation: Imbalanced water can cause discomfort for swimmers.

• Poor water circulation: High TDS can make water feel thick or sticky, reducing its ability to flow properly through the filtration system.

How to Test for TDS in Pool and Hot Tub Water

Checking your TDS levels is easy with the right tools. Here’s how:

1. Use a TDS Meter: A digital TDS meter provides quick and accurate readings.

2. Take a Water Sample: Collect a sample from the pool or spa and test it using test strips or liquid test kits.

3. Compare to Recommended Levels: The ideal TDS range varies:

• Swimming Pools: Below 2,000 ppm

• Hot Tubs: Below 1,500 ppm

• Saltwater Pools: Up to 5,000 ppm (due to added salt)

What Causes High TDS Levels?

Several factors contribute to rising TDS levels, including:

• Evaporation: As water evaporates, minerals and chemicals remain behind, increasing TDS.

• Chemical Additions: Every time you add chlorine, stabilizer, or algaecide, TDS increases.

• Swimmer Contaminants: Sweat, sunscreen, and lotions add organic matter to the water.

• Source Water Issues: Some water supplies naturally contain high levels of minerals and metals.

• Poor Water Circulation: Inadequate filtration allows dissolved solids to accumulate.

How to Lower TDS Levels

If your TDS is too high, you’ll need to take action. Here’s how:

1. Drain and Refill the Water

• The most effective way to lower TDS is to partially or completely drain and refill your pool or hot tub with fresh water.

• For pools, consider draining 25-50% of the water and refilling it.

• For hot tubs, draining every 3-4 months prevents excessive TDS buildup.

2. Use a Reverse Osmosis (RO) System

• Some pool professionals offer reverse osmosis filtration, which removes TDS without draining the pool.

• This is a more eco-friendly option, but it may not be available everywhere.

3. Maintain Proper Filtration

• Run your filter daily to remove dissolved solids before they build up.

• Clean or replace your filter cartridges regularly to keep the system efficient.

4. Reduce Chemical Overuse

• Be mindful of how many chemicals you add to the water.

• Only use what’s necessary, and avoid excessive algaecide or stabilizer use.

How to Prevent High TDS Levels

Keeping your TDS in check requires consistent maintenance. Here are some key prevention tips:

• Test water regularly: Monitor TDS levels at least once a month.

• Control chemical use: Add chemicals only when needed and avoid overuse.

• Encourage swimmers to rinse off: Showering before entering the pool or spa reduces organic contaminants.

• Drain and refill water periodically: Regularly replacing old water with fresh water prevents TDS buildup.

• Use high-quality chemicals: Cheap chemicals often contain fillers that contribute to higher TDS.

Common Myths About TDS

There are a few misconceptions about TDS that can lead to confusion:

❌ Myth: High TDS always means bad water quality.

✅ Truth: Some dissolved solids (like salt in a saltwater pool) are normal and necessary.

❌ Myth: Shocking the pool will lower TDS.

✅ Truth: Shock treatments kill bacteria and algae but do not remove dissolved solids.

❌ Myth: You can filter out TDS with a standard pool filter.

✅ Truth: TDS particles are too small to be removed by regular filtration.

Key Takeaways

Understanding and managing TDS levels is essential for maintaining balanced, high-quality water in your pool or hot tub. By testing regularly, minimizing chemical overuse, and refreshing the water when needed, you can prevent the negative effects of high TDS and keep your water clean and clear.

By staying proactive, you’ll enjoy a healthier, more inviting pool or spa while extending the life of your equipment and reducing maintenance costs.