Clearing The Water

What happens when a routine water analysis indicates the water in a swimming pool or hot tub is chemically balanced, but the water appears less than perfect?

Make sure you're doing the right tests.

Too often a pool operator’s solution is to blindly add more chemicals and perform unscheduled maintenance on equipment, which can waste precious time and money. Additional testing is often forgotten about unless it is to verify the initial result.

Performing a secondary test can easily identify the root problem, making treatment more simple and cost-effective.

Let’s assume that primary routine testing includes chlorine (free and total), pH, total alkalinity, total hardness and cyanuric acid (for outdoor pools). Although not performed as frequently, cyanuric acid and hardness testing are certainly of primary importance, and should be performed on a regular basis. Additionally, if a swimming pool is maintained with phosphate-removal chemicals, the testing of phosphates is also of primary importance.

Other testing is considered secondary, and often gets overlooked. Therefore, if all of the regular primary tests appear to be within specification, yet the water is still less than optimal, it is time to consider some of these secondary tests. Here are a few of the most common to consider:

• Nitrates

• Metals

• Total dissolved solids


Nitrate is a nitrogen compound that forms naturally in the soil and atmosphere, and can also be present in water. Having nitrate contamination is like hosting rude in-laws during the holidays–they never leave quickly enough, and getting rid of them is hard to do. Nitrate nitrogen is extremely stable in water. As a result, its stay in pool or spa water can be an extended one.

Nitrates can be introduced to water through a number of sources. The water used to fill the swimming pool or hot tub may contain nitrates, especially if well water is used.

Fertilizer is another common source of nitrate intrusion. Many fertilizers contain a high level of nitrate nitrogen to keep lawns and plants plush and green–obviously not the ideal color for a swimming pool. Nitrogen from fertilizers can be washed into the swimming pool by rain, wind, bathers or animals, or can result from the overspray of an overzealous lawn service or golf-course maintenance person.

Other sources of nitrate nitrogen are human and animal wastes, rain, leaves or other decaying plantlife.

Any one source can introduce a significant numbers of nitrates into the water. However, a problematic buildup can occur over time as a source continuously contributes nitrates. Likewise, a combination of these sources may build up even more quickly, which can have an even greater impact on water quality.

Why it should be tested: In well-balanced water, nitrates will increase sanitizer demand, causing water to require higher-than-normal dosages of chlorine, bromine or other sanitizers.

Even a small amount of nitrate — around 10 parts per million (ppm) — can affect the sanitizer demand. Algae can also become an issue with high nitrate levels.

Keep a test kit on hand.

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