Getting your swimming pool ready for the pool season is an essential step.
A successful pool opening will allow you to enjoy crystal clear, disinfected and well balanced water throughout the summer months.
We advise to restart your pool when the water temperature is consistently above 15°C (59 °F)
- This will prevent the rapid growth of algae and micro-organisms in the water.
- It will also protect the liner and equipment from the development of biofilm, limescale deposits and dirt.
Before being able to swim in your pool, and to start the season in the best possible conditions, there are a few steps to follow:
Key steps for reopening the swimming pool:

1. Remove winter covers
- Remove the cover (winter cover or shutter).
- Clean it before storing it to prevent mould and odours.
- Remove winterising devices: plugs, gizzmos, floats.
- Reinstall the skimmer baskets.
2. Clean the pool
- Check that your equipment is working properly (filter, pump, etc.).
- Clean the water line and skimmers with HTH BORKLER GEL
- Remove dirt from the pool using accessories (brushes, skimmers, vacuum cleaner, etc.)
3. Clean the filter
- Descale the sand filter or cartridge filter with HTH FILTERWASH
- Adjust the pool water level to halfway up the skimmers.
- Restart the filtration system for at least 24 to 48 hours.

3 & 5 liters
HTH FILTERWASH is a coloured liquid, which makes it easier to rinse out.
Effective on sand, diatomaceous earth and cartridge filters, this innovative product offers a powerful solution for removing impurities and limescale, thereby extending the life of your filters.
4. Analyse and balance the water
- Check the pH and readjust if necessary with HTH pH PLUS to increase it or HTH pH MINUS to lower the pH
- Monitor the TAC and maintain it between 8°F and 14°F (80 to 140 mg/l). Adjust it gradually by 3°F at a time with HTH ALKANAL
5. Shock treat the water
- Shock treat the water with HTH SHOCK powder at a rate of 150 g per 10 m³ of water, keeping the filtration system running for at least 24 hours (repeat the treatment 48 hours later if necessary)
– Oxidises organic matter
– Clears green water
– Prevents the proliferation of micro-organisms and algae

with handle and measuring cap
6. Set up a regular pool treatment
Carry out the weekly maintenance treatment:
- Check the pH, disinfectant (chlorine or bromine), and TAC levels
- Disinfect the water at a rate of one HTH STICK per 20 m³ of water every 4 to 5 days

- Every other week: shock treat the water with HTH SHOCK powder at a rate of 150 g per 10 m³ of water, keeping the filtration system running
- For crystal clear water, insert a flocculant cartridge HTH REGULARFLOC for 25 m3 in the skimmer every fortnight (for pools equipped with a sand filter)
In conclusion :
Step by step, you’ve brought your pool out of its winter rest, just like opening up a holiday home for the season. Each step matters: cleaning, testing, adjusting, and gradually restoring the water until it is clear, clean, and safe. By following this simple guide, you now have everything you need to open your pool safely and with confidence.
The season can begin — your pool is ready for you.
DO NOT MIX CALCIUM HYPOCHLORITE WITH ANY OTHER TREATMENT PRODUCT.
NEVER DISSOLVE BEFORE USE.
USE BIOCIDAL PRODUCTS WITH CARE.
BEFORE ANY USE, READ THE LABEL AND THE PRODUCT INFORMATION CAREFULLY.