When summer’s here and the heat is high, the last thing anyone really wants to worry about is keeping their swimming water clean and fresh. Inexpensive and easily available, chlorine has been the method of choice for decades. But problems with allergies, skin irritation, and mucus membrane sensitivity led swimming pool designers and engineers to develop new methods for water sanitation. Here’s an introduction to the three of the most popular chlorine alternatives:

Saltwater: Saltwater sanitation systems are increasingly popular in new pool installations. Saltwater systems work through the principle of hydrolysis, a process that converts water and food-grade salt into pure sodium hypochlorite. Hypochlorite is the primary active ingredient in chlorine. Saltwater systems are a way to get the benefits of chlorine without the chemical additives and stabilizers of conventional chlorine.  One drawback to saltwater systems is that the water can cause corrosion in fittings, pipes, and drain grates as well as the underwater lighting fixtures.

Ionizers: Ionizers use a low electric current to create copper and silver ions that attract and kill algae, bacteria, and viruses. The two most common ionizer systems use either an electric ionizer, which uses electricity to charge the ions, or the mineral cartridge ionizer, which capitalizes on the water’s flow through a mineral cache to release a steady stream of ions. Ionizers do not oxidize the water and the systems are very expensive, but the diodes only need to be replaced every three to five years and the ionized water does not harm pool equipment.

Bromine: Conventional wisdom dictates that chlorine is for pools and bromine is for spas, but pool owners who want to avoid the clouds of chloramine gas generated by the pool’s sanitation process often opt for bromine, which remains in its liquid state and retains its sanitizing effectiveness, unlike chloramine, which does not. Because bromine becomes unstable in sunlight, it is best used for indoor pools and spas. It’s also a weaker oxidizer, so it takes longer to break down waste in the pool. On the bright side, while bromine does generate an odor, it is nowhere near as pungent and irritating as the smell of chloramine gas.