After a streaming and red-eyed experience while swimming in a local pool, I got in touch with Belfast City Council to see if they could let me know what chemicals are used in council swimming pools. After a long wait, I got the following list of chemicals from the manager of the pool:
Calcium Hypochlorite tablets are used to generate Chlorine that is required to destroy the organic contaminants in the water.
Poly Aluminium Chloride is a flocculation agent which helps the sand filters to remove very finely suspended matter and algae, colouring matter and a portion of the bacteria in the water.
CO2 gas is used for pH control while Ozone and UV treatment is used for pool disinfection and helps reduce the level of chlorine required in the pool.
Liquid Algaecide kills or inhibits the multiplication of algae in the pool.
Sodium Bicarbonate is used to raise pH while Sodium Bisulphate is used to lower pH.
Chlorine is used in all Belfast City Council pools. A few pools in the UK use Bromine-based disinfectants but apparently there are doubts about the evidence for their effectiveness as compared to chlorine-based disinfectants. With heavy bather loads, such as in Belfast pools, Chlorine use is recognised as best practice within the industry.
After an on-line search, I found this site, which explains that eye irritation usually arises because of an inadequate water-balancing process (i.e. the relationship of different chemicals to each other in the pool). Therefore, it would appear that the red eyes occurred due to an inadequate amount of chlorine in the pool.