How is salt different from chlorine?
Salt electrolysis produces chlorine in the water on the spot: ordinary salt is added (usually 3 to 5 g/l; the sea is about 35 g/l) and the cell converts it to hypochlorite, which disinfects the water and then reverts to salt. So a saltwater pool is not chlorine-free: it runs on chlorine it makes itself.
Advantages: water that feels softer, no strong chlorine smell, no storing or dosing of chemicals, lower reagent spend. Drawbacks: the cell costs money and needs replacement, salt affects stone and metals, and pH rises with electrolysis, so acid dosing is needed. Tablet or liquid chlorine is cheaper at the start but needs manual control and storage of chemicals.
Does a saltwater pool damage the surrounding stone?
It can, if the stone is porous. Salty splashes evaporate on the stone, salt crystallises in the pores and gradually crumbles the surface. Limestone, travertine and marble are especially vulnerable. Dense materials (granite, porcelain, dense limestones with sealer) tolerate salt far better. The same applies to overflow channels and pool coping.
What to do: choose dense stone or porcelain, seal porous materials with water repellents, rinse the surround with clean water and drain the splash zone. Metal suffers too: ladders, lights, fixings and heat exchangers are made of 316 steel or titanium. If the project is already under way with porous stone, it is better to choose another disinfection system or lower the salt concentration.
Does UV replace chlorine?
No. A UV lamp destroys bacteria and viruses as water passes it and breaks down the chloramines that cause smell and eye irritation. But UV has no residual effect: after the lamp nothing protects the water, and the pool still needs a small dose of chlorine or another disinfectant to keep the water safe in the pool itself.
So UV is used as a supplement, and its great advantage is that it lets you keep chlorine low, giving softer water without smell. The lamp is replaced about once a season and the quartz sleeve cleaned. For a family with children or sensitive skin it is a good option combined with electrolysis or a low chlorine dose. As the only system in an outdoor pool it is not enough.
What is best for children and skin?
Irritation usually comes not from chlorine itself but from chloramines, compounds of chlorine with organic matter (skin, sweat, cream), and from the wrong pH. So water stability matters more than the system type: pH around 7.2 to 7.6 and free chlorine low but sufficient, as your service advises. Automatic control keeps these values steadier than someone who comes once a week.
A saltwater pool feels subjectively softer, UV helps cut the smell, and oxygen or peroxide systems smell pleasant but need frequent dosing and are less reliable in sun. For children a combination works best: electrolysis or a low chlorine dose, UV for chloramines, automation for pH and a shower before entering. Ask a paediatrician if your child has allergies.
Can you monitor pool water from another country?
Yes. Modern controllers measure pH, redox potential (ORP), sometimes free chlorine and temperature, dose acid and chlorine themselves and connect to the internet. You see readings in an app, receive alerts and change the filtration mode and season. This is not science fiction but standard villa automation.
Reliability depends on the probes, their upkeep and calibration: probes age and lie, so once a season the service company checks them. Add water level with automatic top-up, a leak sensor and backup power for the controller. Automation saves visits but does not replace them: a person on site is needed to empty baskets, check the pump and notice what a probe cannot.
What to choose for a house you do not occupy all year
For a part-time house three principles apply. First: automation with probes and dosing, so the water stays in range without you. Second: a system that needs no manual chemistry or chemical storage: salt electrolysis or a stable low chlorine dose, plus UV. Third: a service agreement with regular visits and a pool cover (blind, cover) while you are away, to reduce dust and evaporation.
Do not leave the pool without circulation: stagnant water turns green quickly. A variable-speed pump runs at minimum a few hours a day and saves electricity. For long absences there is a "hibernation" mode that the service sets. The choice between salt, chlorine and UV is made together with the choice of finishes and the surrounding stone, not separately.
Where to start and how BCN YARD can help
Start with how you use the house: how many months a year, who swims, who keeps watch. Then choose the disinfection system, the surrounding materials and the automation so they do not clash. That way the decision does not have to be redone after the first season.
BCN YARD builds and renovates pools in Russian and Spanish, with one person responsible for the site. We visit the plot, see what is there and include the water system in the overall project, with a phased estimate.
Frequently asked questions
Does pool water need replacing every year?
Usually not, if the water is under control: filtered, balanced and without stabiliser build-up. Partial changes and filter backwashes follow the service schedule. A full drain is rare (for repairs or heavy contamination) and requires deciding where the water goes.
Which pool heating works with salt?
Heat pumps are suitable, but the exchanger in salt water must be titanium. Electric heaters and ordinary steel corrode. The choice is made together with the water system: if heating is already installed, check the exchanger material before switching to salt.
Is salt a danger to pool tile and mosaic?
Ceramic and glass mosaic do not fear salt, but grout and adhesive must be rated for pools. Problems begin with porous natural stone and poor joints. That is why the grout and adhesive are specified in the project and checked during laying.