Starting up the pool after winter: What do you need to do?

This advice is part of the ‘All about saltwater pools: Your complete guide’ series.

The first rays of sunshine break through, temperatures rise and the garden starts turning green again. For pool owners, this means only one thing: it's time to wake the pool from its winter slumber. Getting your pool ready for summer is an annual ritual that determines the rest of the swimming season.

A good start-up not only results in crystal-clear water, but also prevents technical problems and unnecessary costs later in the year. But where exactly do you start? Should you refresh the water? In what order do you add chemicals? And how do you check whether the technique has survived the winter well?

In this blog post, we take you step by step through the process. We have drawn up a clear plan so that you can get to work efficiently and enjoy your first dip in no time.

When is the right moment?

Many people wait until the first heatwave before opening the pool. That is actually too late. As soon as the water temperature rises above 12 to 15 degrees, algae and bacteria start to develop.

The best time to start is in spring (March or April), as soon as the risk of severe night frost has passed. By starting on time, you get ahead of algae growth and have plenty of time to get the water balance in order before the real swimming weather arrives.

Step 1: Removing and cleaning the winter cover

The first step is literally unveiling your pool.

  1. Remove dirt and water from the cover: Your winter cover probably has a layer of leaves and rainwater on it. First pump this water away with a submersible pump and scoop off the leaves. Prevent this dirty water from getting into your clean pool water when removing the cover.
  2. Take off the cover: Preferably do this with two people. Carefully fold up the cover.
  3. Cleaning and storing: Clean the winter cover immediately with water and a soft brush. Let it dry thoroughly before folding it up and storing it in a dry, mouse-free place. This way, it will be ready for use again in autumn.

Step 2: Cleaning and filling the pool

Now that the pool is uncovered, you can see how the water has fared through winter.

  1. Removing coarse dirt: Use a skimmer net to fish leaves, twigs and insects out of the water. Do this thoroughly, as organic dirt breaks down chlorine and feeds algae.
  2. Topping up the water level: During winter, the water level has probably dropped. Top up the pool with tap water to the normal level (usually halfway up the skimmer opening). Make sure the level is high enough before switching on the pump, otherwise it will suck in air.
  3. Waterline cleaning: You will often see a limescale or dirt line on the waterline. Use a special waterline cleaner and a soft sponge to scrub this clean. Do not use aggressive household products, as these disrupt the water balance.

Please note: Do I need to refresh all the water?
Usually this is not necessary, unless the water is extremely dirty or if your stabiliser level (cyanuric acid) has risen far too high in previous years. In that case, spring is the ideal time to refresh (part of) the water.

Step 3: Checking the technical installation

Before you plug it in, a technical inspection is necessary. During winter, frost may have caused damage or rubbers may have dried out.

  • Connecting: Have you loosened couplings or removed plugs to prevent frost damage? Tighten everything again and put the drain plugs back in the filter pump and the filter tank.
  • Lubricating: Check the rubber O-rings of the pump lid and the couplings. Lubricate them with some petroleum jelly or silicone grease if they are stiff. This prevents leaks.
  • Filter medium check: Look inside your sand filter. Is the sand still loose and clean? Filter sand lasts about 3 to 5 years, filter glass up to 10 years. If the sand is clumpy or dirty, this is the time to replace it.

Step 4: Starting up the pump and circulating

Everything connected and water level correct? Then you can switch on the pump.

  1. Set the 6-way valve to ‘Circulate’ or ‘Filter’: Start filtering.
  2. Venting: If the pump is positioned above the water level, it may take a while before it draws in water. If necessary, open the air release valve on the filter tank until water comes out instead of air.
  3. Backwash: It is wise to thoroughly rinse the filter first by setting the valve to ‘Backwash’ (always switch off the pump first when changing the valve setting!). Rinse for 1 to 2 minutes, switch off the pump, set the valve to ‘Rinse’ for 30 seconds and then set it to ‘Filter’.

Now let the pump run continuously for at least 24 to 48 hours to mix and filter the water thoroughly.

Step 5: Water balance and chemical treatment

Now comes the most important part: the chemistry. In cold, stagnant water, the values have probably shifted considerably.

1. Measure the values
Use a reliable tester (test strips, drop tester or digital meter) and measure:

  • The pH value (acidity)
  • The alkalinity (TA)
  • The chlorine level

2. Correcting alkalinity (TA)
Always start with the alkalinity. This is the buffer of your water. If the TA is too low, your pH value will fluctuate wildly. The ideal value lies between 100 and 150 ppm. Is it too low? Add TA+.

3. Correcting the pH value
Only once the TA is correct should you look at the pH. This is the basis for proper disinfection. The pH should lie between 7.2 and 7.6.

  • Is the pH too high? Add pH-minus.
  • Is the pH too low? Add pH-plus.
    Always dissolve granules in a bucket of lukewarm water first before pouring it into the pool, to prevent staining of the liner.

4. Chlorine shock (shock treatment)
Once the pH is between 7.2 and 7.6, you can start disinfecting. Because the water has been standing still for a long time, it needs a boost to kill all bacteria. Carry out a chlorine shock.

  • Use chlorine granules or fast-dissolving tablets for this.
  • Follow the dosage on the packaging for a shock treatment.
  • Let the pump run continuously so that the chlorine spreads properly.

Do you have a salt water pool?
Then first check the salt level. Add salt if necessary and let it dissolve for 24 hours while the pump is running, before switching on the salt chlorinator. You could also carry out a manual chlorine shock to give the system a helping hand at the start.

Step 6: The final stretch

After the chlorine shock, the water may become slightly cloudy or take on an odd colour for a while. This is normal; the chlorine is reacting with the dirt. Keep filtering until the water is clear.

  • Flocculant: Is the water still a bit milky after 2 days? Then use a flocculant to bind the finest dirt particles together, so your filter can capture them.
  • Temperature: Now you can switch on the heating (heat pump). Keep in mind that heating cold water (for example from 10 to 28 degrees) can take several days. Cover the pool well at night to prevent heat loss.

Common mistakes when starting up

To help you a bit further, here are a few pitfalls you'll want to avoid:

  • Adding chemicals at the same time: Never add chlorine and pH products to the water at the same time. This can create dangerous gases and cause the products to counteract each other. Always leave a few hours (and circulation) in between.
  • Running the pump for too short a time: During the start-up phase, the water needs to be in continuous motion. Don't save on electricity now, as it will cost you more in chemicals later to get the water right again.
  • Forgetting to measure: “I'll just add some by feel” is the fastest route to problems. Measuring is knowing. Without the correct pH value, your chlorine does almost nothing.

Conclusion

Starting up your pool takes a bit of time and attention, but it's not rocket science. By following the right order – cleaning, checking the technical equipment, restoring the water balance – you lay the foundation for a carefree summer.

Have you gone through all the steps and is the water crystal clear and at temperature? Then there's only one thing left to do: put on your swimming trunks and enjoy that first, well-deserved dip!

Do you still have questions about specific products after reading this step-by-step guide, or are you struggling with your water values? Feel free to contact us, we're happy to help you further.