Freshly Filled Pool Chemical Guide

What start-up chemicals are needed for a new pool, or for a pool that has been drained and refilled with fresh water?

That depends on the water balance of your source water. Some tap water makes excellent pool water, while other sources need major chemistry adjustment. It's critical to achieve a water balance that works well with chlorine and won't stain, scale, fade, or corrode your soft and shiny pool surfaces.

Refilling a Pool with Fresh Water

Thankfully, you have choices — fill from the hose, fill from a truck, or fill from a nearby fire hydrant. Most people opt for the garden hose pool filling method, often using two hoses where possible.

If your water is from a well, or if your source water contains silt or minerals, you can filter the water as you fill the pool. Pleatco's Purestart pool fill pre-filter handles up to 40,000 gallons, and removes sediments and other solid impurities. This can help reduce the risk of staining and hard mineral deposits in your pool.

Testing your Freshly Filled Pool Water

To find out the water balance of your source water, you can use a pool test kit or test strips. Be sure your kit or strips are fresh — last year's supply may produce inaccurate results.

To produce the full array of water tests (Chlorine, pH, Total Alkalinity, Calcium Hardness, and Cyanuric Acid), you will need a complete test kit like the Taylor Deluxe K-2005. If you prefer test strips, the AquaChek Select 7-Way offer a simple, complete testing option.

For the most accurate water analysis, you can always take the water to your local pool store for a free water test. However, you may not need the precise detail these tests offer when you first start the pool up after a fresh refill. An at-home water test will tell you what you need to know to get started. They may not be as accurate, but will often be close enough.

Adding Chemicals for a Newly Filled Pool

Alkalinity Adjustments: It's recommended to start with any adjustments to Total Alkalinity (TA) first, because of its effect on pH levels. If your TA is below 80 ppm, add Alkalinity Increaser. If your TA is above 120 ppm, use pH Decreaser to reduce levels within the ideal range of 80–120 ppm.
pH Adjustments: When pH is slightly low, your chlorine works well. But when it dips below 7.0, the water becomes acidic and slightly corrosive. On the other hand, when pH rises above 8.0, chlorine is very slow to react, and the water becomes very basic, making it prone to cloudy water conditions and scale deposits. Use pH Increaser or pH Decreaser as needed to maintain an ideal pH level of 7.4–7.6.
Calcium Adjustments: For pools in hard water areas, tap water of 400–600 ppm is not uncommon. The ideal range of 200–400 ppm is somewhat flexible, as many pools operate with much higher Calcium Hardness levels without a problem. If your water is soft, meaning levels are below 150–180 ppm, this can cause aggressive water conditions known to cause etching, staining, and mineral deposits. Add Calcium Hardness Increaser to raise Calcium Hardness levels in your pool. If your source water has naturally high Calcium Hardness, you can manage it with a stain and scale control product.
Cyanuric Adjustments: Any body of water will always have a testable level of pH, Total Alkalinity, and Calcium Hardness, whether low or high. But on a newly filled pool, Cyanuric Acid (aka stabilizer or conditioner) levels are usually zero. Chlorine tablets contain stabilizer, but it can take years for levels to build up to an unmanageable level. Boost it up to 30 ppm to start with by adding 3 lbs of Stabilizer per 10,000 gallons of pool water to protect free chlorine from the sun.
Chlorine Adjustments: Lastly, after you have tested and separately added any necessary adjustment chemicals to the pool, you can raise the chlorine level. Granular chlorine (pool shock) is most often used to quickly raise the chlorine to levels high enough to oxidize (destroy) any contaminants, pathogens, or combined chlorine molecules. Follow label directions for dosage and treatment guidelines for freshly filled pools.

Chemicals Needed for Pool Start Ups

We also have spring Pool Start-Up Kits, which are pool chemical packages specifically geared toward new pool start-ups. These kits are most commonly used when re-opening a pool in the spring, but they work great for fresh pool refills, as well. Start-Up Kits for pools contain Stain and Scale Prevention, Pool Shock, Algaecide, Clarifier, Test Strips, and a Sun-Sorb oil absorbing sponge. Bundled pool start-up chemicals save a considerable amount over purchasing items separately.

Tips for Adding Start-Up Pool Chemicals

Add a stain and scale preventative first, especially for new plaster.
Try PoolCalculator.com for amounts of start-up chemicals needed, or refer to the product label for dosage instructions.
Add one chemical at a time, using a pool brush and your pool pump to distribute.
Run the filter pump while adding chemicals to circulate.
Allow ample time between adding chemicals to prevent an adverse chemical reaction.
Re-test the pool water after 8 hours of pump run time.
Add chlorine shock when the sun is not directly overhead.
Add algaecides last, after the chlorine level drops below 3 ppm.
See our Pool Start-Up Kits for all the specialty and sanitization chemicals needed.

Once the pool is opened, you will need to circulate, filter, clean, and treat the pool water daily. Consistent water balance, constant chlorine levels, and effective filtering is important to prevent water problems.

As the water temperature and pool usage increase through the summer, you will need more hours of daily filtering, and more chlorine tablets to maintain sanitization and water clarity.

Pool Start-Up Chemicals for Refilled Pool